The British Rail Class 117 represents one of the most successful diesel multiple unit designs in British railway history, serving continuously for forty years from 1959 to 2000 across four BR regions and achieving the distinction of becoming the largest preserved first-generation DMU class with 51 surviving vehicles. Built by the Pressed Steel Company at Linwood, Scotland between 1959 and 1961, these elegant three-car suburban units combined the proven Derby Lightweight design philosophy with crucial enhancements including toilet facilities and distinctive roof-mounted headcode boxes that differentiated them from their Class 116 cousins. For model railway enthusiasts, the class enjoys exceptional representation through Bachmann's laser-scanned OO gauge range and Heljan's comprehensive O gauge collection arriving December 2025.
The Class 117 DMU emerged during British Railways' ambitious first-generation dieselisation programme, specifically designed to replace steam-hauled suburban services out of London Paddington with modern, economical traction. The 123-vehicle order delivered thirty-nine complete three-car sets plus three spare pairs of driving motors, initially allocated exclusively to the Western Region at Reading and Southall depots. The distinctive combination of 300hp per power car, comfortable accommodation for 230 passengers across first and second class seating, and reliable Leyland horizontal diesel engines established the class as the backbone of Thames Valley suburban operations throughout the 1960s-1970s.
From their elegant early years in BR green livery working London commuter services through progressive deployment to Birmingham Cross-City routes, Scottish Fife Circle duties, and unexpected Cornish branch operations, the Class 117 demonstrated remarkable versatility and longevity. The final units operated scheduled services until 2000—an extraordinary forty-year career that vindicated the Derby design philosophy whilst creating extensive photographic and enthusiast documentation. This comprehensive service history combined with successful organised preservation ensures the class remains highly visible on heritage railways and thoroughly accessible to modellers seeking authentic first-generation DMU representation.
Quick Takeaways
- 123 vehicles constructed: Pressed Steel Company delivered 42 DMBS, 39 TCL, and 42 DMS vehicles between 1959-1961, forming 39 complete three-car sets plus spare power cars
- Dual Leyland engines: Each driving motor carried two Leyland 680 horizontal six-cylinder diesels producing 150hp each for total 600hp per three-car unit with mechanical transmission
- Forty-year service span: From 1959 Western Region introduction until final Silverlink withdrawal in 2000, encompassing BR green, blue, blue-grey, Network SouthEast, and Regional Railways eras
- Progressive gangway modifications: Originally non-gangwayed for dense suburban work, all vehicles received corridor connections between 1965-1972 enabling flexible formations and strengthening
- National deployment diversity: Initially London Paddington suburban work, expanding to Birmingham Cross-City, Scottish Fife Circle, Cornish branches, and Gospel Oak-Barking services across four regions
- Exceptional preservation success: 51 vehicles survive across 20+ heritage locations including mainline-certified Swanage Railway set and operational Scottish, Welsh, and English heritage railway units
- Comprehensive model availability: Bachmann OO gauge range offers multiple livery variants at £459.95-569.95, Heljan O gauge models arriving December 2025 at £699-1,049 RRP
Historical Background and Context
The genesis of the Class 117 lay in British Railways' groundbreaking first-generation diesel multiple unit development programme, initiated with the November 1952 announcement of £500,000 expenditure for lightweight diesel railcar trials. The revolutionary Derby Lightweight prototypes of 1954-1955 pioneered aluminium-alloy construction techniques with 57ft 6in underframes and 150hp AEC diesel engines, establishing fundamental mechanical and structural concepts that would define British diesel multiple unit practice for the next two decades.
The British Transport Commission's 1955 Modernisation Plan provided the financial framework for mass production of standardised DMU designs developed from the Derby prototypes. The plan earmarked substantial investment for replacing steam-hauled suburban and branch services with economical diesel traction, recognising that multiple unit operation offered crew savings, rapid acceleration, and simplified maintenance compared to locomotive-hauled formations requiring engine changes, coaching stock movements, and larger depot facilities.
On 16 October 1958, the British Transport Commission announced its Western Region dieselisation scheme, originally specifying 168 vehicles split between two constructors. Birmingham Railway Carriage & Wagon Company received orders for 45 vehicles that became the Class 118, whilst the Pressed Steel Company secured the larger contract for 123 vehicles—the order that produced the Class 117 DMU. This allocation reflected Pressed Steel's established expertise in lightweight alloy construction and modern production techniques at their Linwood facility near Glasgow.
The Class 117 design represented a licence-built variant of the Derby-designed Class 116, but incorporated crucial modifications reflecting its intended longer-distance suburban role serving routes from London Paddington to Reading, Oxford, and beyond. The most significant enhancement involved fitting toilet facilities in the trailer composite vehicle—essential for journeys exceeding 30-40 minutes where passenger comfort demanded such amenities. Additionally, the class received distinctive four-character roof-mounted headcode boxes for route identification, contrasting with the simpler disc-code systems employed on shorter-range suburban units.
Insider Tip: Recognition Features
You can distinguish Class 117s from the similar Class 116 by examining three key features: the prominent four-character headcode box mounted on the roof above the driver's cab (Class 116 used simpler disc codes on the cab front), the presence of toilet facilities in the centre trailer car indicated by small roof vents, and the slightly different body profile with deeper windscreens. When modelling authentic formations, note that early units operated without gangway connections until the 1965-1972 modification programme, creating two distinct visual variants for different periods.
Pressed Steel delivered the fleet across three manufacturing lots between 1959 and 1961. The company constructed 42 DMBS (Driving Motor Brake Second) vehicles numbered 51332-51373, 39 TCL (Trailer Composite with Lavatory) vehicles numbered 59484-59522, and 42 DMS (Driving Motor Second) vehicles numbered 51374-51415. This vehicle allocation provided thirty-nine complete three-car sets designated for immediate traffic plus three spare pairs of driving motors enabling flexible deployment and maintenance cover.
The initial formation pattern comprised DMBS+TCL+DMS three-car sets, seating 230 passengers with a 65-seat brake second compartment, 24 first-class and 50 second-class seats in the lavatory composite, and 91 second-class seats in the driving motor second. This capacity reflected the intensive suburban passenger flows the units would handle on Thames Valley routes where standing passengers during peak periods would significantly increase actual loadings beyond seated capacity.
Contemporary railway periodicals praised the modern styling and passenger amenities. The distinctive Pressed Steel bodywork featured large picture windows providing excellent passenger sightlines, streamlined cab fronts with curved windscreens, and elegant body lines emphasising horizontal emphasis through waist-level chrome strips. The interior appointments included comfortable moquette seating, fluorescent lighting (after later refurbishment), and toilet facilities rare in suburban rolling stock of the period—features that established passenger expectations for modern diesel multiple unit comfort.
Design and Technical Specifications
The engineering excellence of the British Rail Class 117 centred on the proven Leyland 680 horizontal six-cylinder diesel engine, a powerplant selected for reliability, accessibility, and proven service in road transport applications adapted for railway use. Each driving motor vehicle housed two complete Leyland engines, each producing 150hp at 1,800rpm for total output of 300hp per power car and 600hp per complete three-car unit. This conservative power rating reflected British Railways' preference for reliable moderate-power units rather than highly-stressed installations requiring intensive maintenance.
The mechanical transmission system employed R14 four-speed epicyclic gearboxes manufactured by Self-Changing Gears Ltd, paired with F239 final drive units delivering power to the driving axles. This proven transmission arrangement provided smooth power delivery across the speed range whilst enabling rapid acceleration from station stops—crucial for intensive suburban operation with frequent intermediate calls. The epicyclic design offered simplified maintenance compared to sliding-mesh alternatives, reducing depot workshop requirements and enabling quick component replacement during routine servicing.
The vehicle dimensions reflected the Derby Lightweight heritage with bodies measuring 64ft 6in (19.66m) in length and 67ft 1in (20.45m) over buffers, providing generous passenger accommodation within the British loading gauge restrictions. Width measured 9ft 3in (2.82m), typical for BR standard coaching stock, whilst height reached 12ft 8½in (3.87m) including roof equipment. These proportions created comfortable internal spaces with adequate headroom and generous seating arrangements whilst maintaining compatibility with platform clearances and tunnel profiles across the Western Region network.
Weight distribution was carefully calculated to balance passenger capacity against axle loading restrictions. Power cars weighed 36 long tons each in working order, with trailer cars at 30 tons, producing total formation weight of approximately 102 tons for a complete three-car set. This modest weight enabled operation across lightly-built branch lines whilst providing sufficient adhesion for reliable acceleration with fully-loaded passenger consists. Each driving car carried 560 imperial gallons of fuel in underfloor tanks, providing operational range adequate for typical diagram patterns involving 150-200 miles between refuelling.
The braking system utilised vacuum brake technology with Gresham & Craven quick-release equipment, standard for British Railways diesel multiple units of the period. The vacuum system provided reliable stopping power whilst remaining compatible with locomotive-hauled coaching stock should mixed formations prove necessary for special workings or emergency substitution. Some units later allocated to Birmingham Cross-City received air brake retrofits enabling operation alongside Class 115/116 units already so equipped, creating technical variations within the class requiring careful attention for authentic modelling.
Bogie design followed Derby practice with fabricated steel frames supporting leaf spring primary suspension and hydraulic dampers controlling vertical movement. The bogies incorporated detailed brake rigging with clasp brakes operating on both sides of each wheel, providing effective retardation from the 70mph maximum speed. On leading bogies of both power cars, speedometer drive connections enabled cab speed indication, whilst trailing bogies carried simpler arrangements without this equipment. The underframe arrangement revealed typical Derby attention to detail, with comprehensive pipework for brake systems, electrical conduits for lighting and control circuits, and fuel tanks carefully positioned to maintain optimal weight distribution.
Technical Innovation: The Gangway Transformation
The progressive gangway addition programme between 1965 and 1972 fundamentally transformed Class 117 operational versatility. Original non-gangwayed units featured solid end panels with emergency access doors, twin exhausts positioned at corridor ends, and fixed formations preventing internal passenger circulation. The modification work installed full corridor connections at all vehicle interfaces, relocated exhaust systems, and modified end panels to accommodate gangway bellows. This enabled passenger movement throughout trains, flexible strengthening with additional trailers borrowed from other classes, and improved passenger perception of spaciousness. For modellers, this creates two distinct authentic variants for different periods—non-gangwayed units for 1959-1965 operations, gangwayed formations for post-1965 service.
The electrical system operated on the standard 110-volt DC supply generated by engine-driven dynamos on each power car, with battery banks providing emergency lighting and control power. Original tungsten lighting fixtures gave way to fluorescent fittings during the comprehensive 1977-1981 Swindon Works refurbishment programme, dramatically improving passenger compartment illumination whilst reducing power consumption. The control systems employed electro-pneumatic contactors for motor control, with driver's controls including power controller, brake valves, direction selector, and auxiliary switches for lighting, heating, and other services.
Passenger accommodation reflected 1950s comfort standards with individual compartment seating in second-class areas and open saloon arrangements in first-class sections. The original moquette coverings used BR corporate patterns in browns and reds, later updated during refurbishment to blue check patterns matching 1970s-1980s corporate image standards. Large picture windows provided excellent sightlines for passengers, whilst forced ventilation systems ensured adequate air circulation before air conditioning became standard on later generation units. The toilet compartment in the TCL vehicle featured contemporary fittings with manual flush systems and washbasin facilities.
Service History and Operations
The British Rail Class 117 entered revenue service in 1959 exclusively on the Western Region, with initial allocations split between Reading depot (code 81D) for gangwayed sets and Southall depot (81C) for non-gangwayed formations. The primary duties centred on intensive suburban services radiating from London Paddington to Slough, Reading, Maidenhead, and surrounding Thames Valley communities where frequent all-stations stopping patterns demanded the rapid acceleration and comfortable accommodation the class provided. Typical diagrams involved 15-20 return trips daily over routes of 10-40 miles, with intensive peak-hour services carrying commuter flows and off-peak shopping and leisure traffic.
From June 1961, Reading-allocated units extended operations beyond Western Region boundaries, working certain Southern Region diagrams between Reading and Portsmouth Harbour via Basingstoke. This inter-regional working demonstrated the operational flexibility built into British Railways' diesel multiple unit fleet planning, with standardised designs capable of seamless cross-boundary operation subject only to route knowledge training and basic technical compatibility. The Portsmouth workings gave Class 117s exposure to Southern Region infrastructure including third-rail electric territory where units operated under diesel power alongside EMUs drawing current from conductor rails.
The fleet spread progressively through Western Region territory during the 1960s as steam-hauled services succumbed to diesel replacement. Cardiff Canton depot received allocations for South Wales suburban services, Plymouth Laira hosted units for Devon and Cornwall branch operations, and Bristol Bath Road operated sets on West Country routes including services to Weston-super-Mare, Taunton, and Westbury. This geographic expansion reflected both the class's proven reliability and British Railways' systematic approach to standardising suburban traction across entire regions rather than maintaining diverse incompatible fleets.
The major gangway modification programme between 1965 and 1972 transformed operational capabilities. The installation of corridor connections at all vehicle interfaces enabled passengers to move freely throughout trains, dramatically improving perceived comfort on longer-distance services where passengers could access toilet facilities regardless of boarding location. Additionally, gangway connections permitted flexible strengthening to four-car or longer formations using additional centre trailers—initially converted Hawksworth coaches from withdrawn steam-hauled sets, later purpose-built Metropolitan-Cammell centre cars borrowed from Birmingham Class 115/116 allocations.
The comprehensive refurbishment programme at Swindon Works between 1977 and 1981 modernised the ageing fleet to extend service lives into the 1980s-1990s. The modifications included fluorescent lighting throughout passenger compartments replacing original tungsten fittings, new formica interior panels updating décor to contemporary standards, blue check moquette seat coverings, exhaust silencers reducing noise pollution, and external repaint from BR rail blue into the distinctive white-with-blue-stripe "refurbished livery" until late June 1979, then the standard blue and grey scheme that became synonymous with 1980s British Rail suburban operations.
Operational Insight: The Cornish Branch Reprieve
One of the most unexpected chapters in Class 117 history occurred when units returned to Cornwall after Class 142 Pacer DMUs proved unsuitable for the tight curves characterising the Looe and St Ives branch lines. The non-bogie Pacers caused excessive rail and wheel wear on the severe curvature, creating maintenance nightmares and infrastructure damage. Class 117s with their conventional bogie designs handled the curves without difficulty, providing reliable service on these scenic routes until Easter 1997 when Class 150 and 153 units became available following cascading from other regions. This demonstrated how older designs sometimes possessed operational advantages over theoretically superior modern replacements.
Under British Railways' Sectorisation reorganisation, Network SouthEast retained Reading-based units for Thames Valley suburban services throughout the late 1980s and early 1990s. The distinctive NSE livery—red, blue, and white stripes with angled (later curved) lining at cab sides—transformed external appearance whilst corporate identity programmes enhanced passenger information systems and service frequency marketing. These units operated intensive diagrams until replacement by Class 165 Turbo diesel multiple units on 28 November 1992, marking the end of first-generation DMU operation on core Thames Valley routes.
The Birmingham Cross-City allocation represented another significant operational sphere. Tyseley depot operated extensive Class 117 diagrams alongside Classes 115, 116, 118, and 121 on the intensive Birmingham-Redditch-Lichfield Cross-City corridor serving dense urban populations. The units handled peak-hour crush loadings with remarkable reliability until electrification brought Class 323 EMUs, with the final DMU workings marked by special "DMU Farewell" headboards on 11 September 1993. Contemporary observers noted the bittersweet atmosphere as forty-year veterans gave way to modern electric traction.
The Scottish chapter began unexpectedly in May 1993 when units transferred to Haymarket depot in Edinburgh for Fife Circle services. The Class 117s worked intensive diagrams from Edinburgh Waverley to Cowdenbeath, Markinch, Dunfermline, and Perth, providing reliable suburban traction whilst ScotRail awaited delivery of second-generation replacements. The units even operated special services for the Open Golf Championship at Carnoustie in July 1999, shuttling spectators between stations and the championship venue. Final Scottish withdrawal occurred on 27 November 1999 when Class 156 Sprinters assumed the diagrams.
Silverlink Metro retained the final operational units at Bletchley depot for Gospel Oak-Barking services and Marston Vale Line duties connecting Bedford with Bletchley. These workings represented the ultimate commercial deployment of Class 117 traction, with progressively decrepit units soldiering on in increasingly worn condition as privatised operators prioritised newer stock. Withdrawal came piecemeal through 2000 as Class 150 Sprinters cascaded from other franchises, finally ending the class's forty-year revenue earning career—an extraordinary longevity that vindicated the Derby Lightweight design philosophy and Pressed Steel construction quality.
Withdrawal and Preservation Legacy
The withdrawal history of the British Rail Class 117 reflected both the inevitable obsolescence of forty-year-old rolling stock and the surprising longevity achieved through systematic maintenance and progressive refurbishment. Unlike many first-generation designs that faced wholesale condemnation following delivery of second-generation replacements, the Class 117 benefited from staged withdrawals enabling organised preservation acquisition of units still in reasonable condition rather than wholesale scrapping of degraded examples.
Early withdrawals commenced as Class 165 Turbo units arrived for Thames Valley services in 1992, with Reading and Southall allocations progressively standing down from November 1992 onwards. The Birmingham Cross-City electrification programme precipitated mass condemnation during 1993 as Class 323 EMUs assumed services, though some units found reprieve through transfer to Scottish or remaining Western Region duties. The systematic approach to withdrawal—driven by specific replacement programmes rather than arbitrary age limits—ensured units remained operational until actual substitutes arrived, maximising asset utilisation whilst minimising premature scrapping.
The final service years saw increasingly decrepit external condition as privatised operators minimised expenditure on vehicles approaching withdrawal. Period photographs from the late 1990s show units with faded livery, patched bodywork, missing components, and general neglect—yet the fundamental mechanical reliability ensured continued operation despite cosmetic deterioration. Enthusiasts documented final workings extensively, creating comprehensive photographic records that now inform heritage railway restoration and model manufacturer research.
The Class 117's late withdrawal proved extraordinarily fortunate for preservation. The final units operated until 2000—well into the preservation movement's maturity when organised societies actively acquired significant rolling stock rather than relying on chance individual rescues. This timing enabled systematic preservation planning, resulting in the largest surviving first-generation DMU fleet with 51 vehicles spread across more than twenty heritage locations throughout England, Scotland, and Wales.
Preservation's Flagship: Swanage Railway Mainline Operations
The Swanage Railway operates the most significant Class 117 preservation project, where vehicles 51356, 59486, and 51388 underwent a £1 million restoration—the most expensive first-generation DMU rebuild ever undertaken in the heritage sector. This comprehensive programme achieved full Network Rail mainline certification, enabling the set to operate scheduled Wareham shuttle services on the national network. Four trains operate daily between Worgret Junction and Wareham station, marking the first heritage DMU revenue service on the mainline since 1972. This achievement demonstrates preservation's evolution from static display to active operational railway contributing genuine transport services whilst showcasing historic traction.
The Swanage Railway's mainline-certified set represents preservation engineering at its finest. The restoration addressed every system to contemporary safety standards: complete body corrosion repairs and repainting, engine overhauls with modern emissions compliance, brake system upgrades including modern relay valves, electrical system rewiring, interior refurbishment matching original specifications, and installation of modern safety equipment including TPWS, AWS, and radio systems. The resulting unit operates to Network Rail standards whilst retaining authentic 1960s character—a remarkable achievement balancing preservation authenticity with operational safety.
The Bo'ness & Kinneil Railway in Scotland acquired set L425 (vehicles 51363, 59510, and 51405) from the Gloucestershire Warwickshire Railway in late 2024, with the unit entering service in early 2025 as a regular scheduled service between Bo'ness and Birkhill. This transfer demonstrated preservation sector cooperation, with surplus stock redistributed to railways requiring additional capacity rather than remaining static at overcrowded sites. The Scottish allocation particularly appeals given the class's operational history on Edinburgh Fife Circle services during the 1990s.
The Epping Ongar Railway operates vehicle 51384 finished in BR green livery, providing Thames Valley modellers with excellent prototype reference for early 1960s appearance. Vehicle 51342 remains under restoration at the railway, with completion anticipated within the next decade subject to volunteer availability and fundraising success. The railway's location on former London Transport Central Line infrastructure creates interesting operational context, with Class 117s serving stations once electrified for tube train operation.
The Strathspey Railway in the Scottish Highlands holds a two-car set finished in BR green "speed whiskers" livery plus a third vehicle under active restoration at Boat of Garten. The railway's spectacular Highland scenery provides dramatic backdrops for photography, whilst the challenging gradients test the units' 600hp capability. Regular operations enable visitors to experience authentic first-generation DMU travel in landscapes far removed from the original Thames Valley suburban context.
The Great Central Railway preserves vehicle 51396, notable for its replacement Class 116 cab featuring the distinctive roof dome absent from standard Class 117 construction. This unique hybrid configuration resulted from accident damage repair using available spare components, creating a one-off variant highly prized by preservation enthusiasts and modellers seeking unusual prototypes. The vehicle typically appears at diesel galas and special events rather than regular service.
The Gwili Railway in Wales operates a complete three-car set providing regular DMU services on this expanding heritage line. The railway's Welsh location seems incongruous given the class's English operational history, yet preservation priorities favour operational utility over geographic authenticity. Visitors enjoy authentic first-generation DMU travel through Carmarthenshire countryside, with the units proving popular for gala events and photographer's charters.
Other significant holdings include the Mid Norfolk Railway, Gloucestershire Warwickshire Railway (retaining vehicles 51360 and 59505 after transferring set L425 to Scotland), and various railway museums maintaining static examples. The geographic spread ensures Class 117s remain visible across Britain's heritage railway network, with multiple sites offering operational experiences and preservation groups sharing technical knowledge, spare parts inventories, and restoration expertise.
The engineering legacy extends beyond preserved vehicles. The Class 117 validated design principles that influenced subsequent DMU development: reliable moderate-power engines rather than highly-stressed installations, comfortable passenger accommodation with toilet facilities, flexible gangway connections enabling formation variations, and robust construction enabling extended service lives through systematic maintenance. These lessons informed second-generation DMU specifications including Classes 150, 153, 155, and 156 that ultimately replaced first-generation types whilst incorporating proven operational concepts.
Modelling Significance and Scale Replications
The British Rail Class 117 presents exceptional modelling significance due to its extensive service spanning five decades across multiple BR corporate identities, combined with the remarkable preservation success enabling contemporary reference photography and dimensional verification. For railway modellers seeking authentic first-generation DMU representation, the class provides compelling prototype appeal enhanced by operational diversity from London suburban services through Cross-City metros to Scottish branch operations, all thoroughly documented in period photography and enthusiast literature.
The modelling landscape remained frustratingly limited for decades despite the class's operational importance. Lima produced OO gauge Class 117 models from 1980 onwards, though accuracy compromises including incorrect headcode box dimensions, oversized roof vents, absence of true DMS vehicles, and crude underframe detailing relegated these to collector's items or conversion fodder rather than serious operational models. The lack of alternative ready-to-run options forced serious modellers toward expensive brass imports or complex scratchbuilding projects requiring advanced skills and substantial time investment.
This changed dramatically when Bachmann Branchline announced Class 117 tooling development in September 2015 during a special Collectors Club event at the Gloucestershire Warwickshire Railway. The company's commitment to laser-scanning preserved example 51360 ensured unprecedented dimensional accuracy, whilst consultation with preservation groups and historical societies provided technical details covering the numerous variations characterising the class throughout its forty-year evolution. The resulting models finally reached enthusiasts in 2020, immediately earning acclaim for exceptional detail quality and thoughtful attention to period-specific variations.
Bachmann's approach demonstrates exemplary commitment to prototype authenticity. Rather than producing a single generic model with alternative running numbers, the company created extensive tooling variations representing the class across its entire service history. The original 2020 release comprised three distinct versions: catalog number 35-500 depicting BR green with speed whiskers, 35-501 showing BR blue and grey refurbished livery, and 35-502 representing revised Network SouthEast corporate image. A limited Kernow Model Rail Centre exclusive 35-500Z provided GW150 chocolate and cream commemorative livery celebrating the Great Western Railway's 150th anniversary.
The 2024 production run expanded the range with additional authentic liveries. Catalog number 35-503 depicts BR green with small yellow warning panels reflecting the transitional period when end panel yellowing appeared before full yellow ends became standard. 35-504 shows set L412 in BR blue livery representing the all-over rail blue scheme that dominated through the 1970s. 35-505 features set 117308 in Regional Railways teal and grey provincial livery applied during the post-sectorisation period. Each version accurately represents specific prototype units with correct running numbers, destination blinds, and period-appropriate detail variations.
The technical execution impresses throughout. Dual five-pole motors with flywheels drive both power cars through carefully engineered underfloor transmission systems, ensuring smooth operation at realistic crawling speeds appropriate for station approaches whilst providing sufficient power for typical four-car formations on moderate gradients. All twelve wheels collect current through comprehensive electrical pickup arrangements minimising stalling on dirty track or insulated point frogs. The diecast metal chassis blocks in both power cars provide satisfying weight (complete three-car set approximately 550g) and low centre of gravity enhancing stability.
Advanced Modelling: Identifying Authentic Period Variants
Bachmann's multiple tooling variations enable period-specific accuracy that serious modellers should exploit for authentic layouts. BR green speed whiskers versions (35-500) represent 1959-1962 original condition with non-gangwayed ends, roof-mounted headcode boxes, no marker lights, cutaway buffers, and original exhaust arrangements. BR green small yellow panel examples (35-503) depict 1962-1967 transitional appearance with developing safety markings. BR blue (35-504) and blue-grey (35-501) versions show post-1965 gangwayed units with corridor connections, marker lights, round buffers, and twin exhausts with silencers. Network SouthEast and Regional Railways liveries (35-502, 35-505) represent 1986-2000 final service period with full corporate branding. Matching locomotive variant to layout era creates authentic atmosphere whilst avoiding anachronistic appearances that undermine credibility.
Detail quality reaches impressive standards for ready-to-run models. Separately applied components include cab-end handrails, lamp irons, multiple working sockets, vacuum pipes, screw-link couplings, and underframe equipment including engines, gearboxes, batteries, fuel tanks, and comprehensive pipework. Factory-fitted glazing includes full interior detail with individually moulded seats, compartment partitions, and driver's desks visible through windows. The underframe treatment particularly impresses, with the complex arrangement of mechanical and electrical systems faithfully reproduced despite most remaining hidden during normal display.
The accessory pack includes alternative parts enabling further customisation: open or closed cab doors, additional underframe pipework for push-pull equipment where fitted, period-appropriate coupling hooks, and destination blind inserts for creating custom route displays. Advanced modellers can detail models further using third-party etched metal components, replacement glazing, custom interior lighting installations, and weathering techniques replicating specific preserved examples or period photographs.
Livery application demonstrates meticulous research and execution. The BR green finish uses correct Brunswick green shade with authentic lining patterns, accurately positioned numberplates and class designation transfers, and proper application of lion and wheel roundels. BR blue and blue-grey schemes show correct corporate colours with white window surrounds and appropriate logo positioning. Network SouthEast livery captures the distinctive red, blue, and white striping with curved cab-end lining matching late-period application standards. Regional Railways teal and grey employs accurate Pantone-matched colours with correctly sized sector branding.
Pricing reflects the quality and comprehensive feature set whilst remaining accessible to enthusiasts. Standard DCC Ready three-car sets retail at £459.95, providing analog DC operation straight from the box with PLuX22 decoder socket in the DMBS guard's van enabling straightforward digital conversion for DCC users. Pre-fitted speakers facilitate sound decoder installation without requiring additional speaker mounting work. Sound Fitted variants retail at £569.95, incorporating factory-installed ESU LokSound decoders with authentic Class 117 sound recordings including Leyland diesel engine notes, transmission sounds, brake squeal, and numerous other effects totalling 20+ controllable functions.
The sound-equipped models merit particular attention. Bachmann recorded actual preserved Class 117 units to capture authentic Leyland engine sounds, transmission whine, and mechanical noises characteristic of the prototype. The sound files include playable horn, guard's whistle, station announcements, door slam sounds, and randomised background effects creating remarkably immersive operational experiences. Critically, sound models operate on both DCC and conventional DC control with basic sound functions available on analogue layouts—a valuable feature for modellers transitioning between control systems or operating dual-standard layouts.
Availability remains strong through all major UK model railway retailers including Rails of Sheffield, Hattons Model Railways, Kernow Model Rail Centre, The Model Centre, and numerous independent stockists. The 2024 production run brought fresh stock after the original 2020 releases sold through, though some variants including the speed whiskers version (35-500) achieved sold-out status by August 2020 and now command premium prices on the secondary market. Collectors seeking complete livery coverage should secure current production versions promptly given Bachmann's tendency toward limited production runs followed by extended unavailability.
For O gauge enthusiasts, Heljan announced its Class 117 range with deliveries scheduled for December 2025. The comprehensive series includes both two-car and three-car formations across multiple livery variants. Three-car sets carry recommended retail pricing of £1,049 (typically discounted to approximately £891 through major retailers), whilst two-car formations retail at £699 (approximately £594 discounted). Livery options cover BR green with speed whiskers, BR green with small yellow panels, BR blue with full yellow ends, BR blue and grey, and Network SouthEast.
Each Heljan O gauge driving car includes a 21-pin DCC interface positioned for straightforward decoder installation, magnetic couplings providing reliable hands-free uncoupling, sprung metal buffers delivering authentic appearance and cushioning, and detailed underframe equipment replicating the complex mechanical arrangements. The models feature high-level exterior detail with separately applied handrails, lamp irons, multiple working cables, and intricate roof equipment. Interior detail includes seating, partitions, and cab fittings visible through glazed windows.
The O gauge market segment particularly values the Class 117 for its moderate size and suburban character. Unlike massive Pacific locomotives or lengthy express coaching stock requiring vast layout space, three-car DMU formations operate effectively on relatively compact O gauge layouts whilst providing authentic British Railways atmosphere. The 1:43.5 scale proportion enables extraordinary detail visibility, with individual rivets, grab handles, and window frames clearly discernible. For modellers committed to O gauge's larger scale, the Class 117 represents an ideal subject balancing prototype authenticity with practical layout operation.
N gauge enthusiasts face complete absence of ready-to-run Class 117 models. Neither Graham Farish, Dapol, nor any other manufacturer produces or has announced N gauge Class 117 tooling. This represents a significant gap given the class's importance and extensive service history. Some enthusiast discussions have explored theoretical 3D-printed body options using modified Dapol Class 121/122 chassis, though no commercial solution exists. The lack of N gauge representation particularly frustrates modellers of compact layouts where the class's moderate length and suburban operation would prove ideal.
The historical Lima OO gauge models from 1980 remain available on the secondary market at £20-60 depending on condition and completeness. These vintage models suffered numerous accuracy compromises including oversized roof headcode boxes (closer to Class 115 than Class 117 proportions), incorrect roof vent arrangements, wrong window spacing, crude underframe mouldings, absence of true DMS vehicles (Lima produced only DMBS and TCL, requiring use of a second DMBS reversed for three-car formations), and basic motor mechanisms prone to high-speed operation. Whilst Lima models enabled Class 117 representation during the decades before Bachmann tooling appeared, they now serve primarily as collector's items or candidates for extensive modification projects rather than serious operational models.
Unique Modelling Tips and Layout Integration
Successfully incorporating British Rail Class 117 models into layout operation requires understanding the specialised nature of their suburban and secondary passenger duties and the authentic operating scenarios that characterised first-generation DMU service during the 1959-2000 period. Unlike prestigious express locomotives working named trains between major cities, the Class 117 was assigned to humble but essential local services connecting smaller communities with main line junctions and major stations where passengers transferred to longer-distance trains.
Authentic operating scenarios should reflect intensive stop-start suburban duties. A typical Class 117 diagram might involve 15-20 return trips daily over a 15-30 mile route with 8-15 intermediate stations, carrying commuters during peak hours and shoppers, students, and leisure travellers during off-peak periods. This service pattern provides excellent operational interest whilst remaining true to prototype practice—each journey involves careful station stops, guard's whistle signals when safe to depart, precise timekeeping essential for intensive timetables with trains following at 15-20 minute intervals, and attention to platform positioning ensuring doors align with platform edges.
Layout design should accommodate the class's operational characteristics and typical infrastructure. Suburban stations with modest 4-6 coach platforms, passing loops enabling intensive service frequency, water columns for replenishing toilet tanks, small engine sheds with basic fuelling and light maintenance facilities, and carriage sidings for overnight stabling all contribute to authentic atmosphere. The infrastructure should suggest secondary importance—no grand overall roofs or extensive passenger amenities, but functional facilities serving working and middle-class communities commuting to larger centres for employment, shopping, and leisure activities.
Weathering Authenticity for Suburban Service
Class 117 weathering should reflect intensive suburban operation whilst maintaining the relatively clean appearance expected of passenger-rated units receiving regular attention at depot cleaning facilities. Focus weathering effects on rail dust and brake dust accumulation along solebar edges, light oil staining around underframe mechanical equipment and bogie bearings, exhaust residue above roof-mounted exhaust outlets, and graduated dirt build-up on lower body panels from track-level grime. Avoid heavy industrial weathering inappropriate for passenger service—these units operated from depots with daily cleaning rosters ensuring presentable external condition between periodic heavy washing. Roof surfaces accumulated urban soot and environmental deposits but remained relatively clean compared to freight locomotives. Interior visible through windows should show light passenger wear rather than industrial grime.
Era selection proves crucial for authentic Class 117 representation. Early period layouts (1959-1965) demand BR green livery with original non-gangwayed formations, roof-mounted headcode boxes displaying appropriate route codes, and period coaching stock including BR Mk1 non-corridor compartment vehicles and parcels vans in matching green livery. The infrastructure should show 1950s-1960s characteristics including semaphore signals, wooden platform canopies, gas lighting transitioning to electric, and steam-era buildings undergoing early modernisation.
Mid-period layouts (1965-1985) can represent the gangwayed blue or blue-grey era with units displaying full corridor connections, all-over rail blue or refurbished blue-grey livery, and contemporary infrastructure including colour-light signals, concrete platform extensions, modern station buildings, and extensive car parking reflecting increased automobile ownership. This period offers maximum operational flexibility, with units working alongside second-generation DMUs (Classes 115/116 on Birmingham services), locomotive-hauled trains (Class 31/37/47 on longer-distance workings), and emerging InterCity services (HSTs on Western Region main lines).
Late period layouts (1986-2000) should show Network SouthEast or Regional Railways corporate identities with distinctive liveries, modern signalling including multiple-aspect colour-lights and AWS/TPWS equipment, updated station facilities with modern shelters and electronic information displays, and contemporary rolling stock including Class 150/153/156 DMUs progressively replacing first-generation types. The infrastructure reflects privatisation-era investment with refurbished stations, improved passenger amenities, and corporate branding promoting specific train operating companies.
Coaching stock selection requires careful attention to period authenticity and operational practice. Class 117s occasionally operated with additional centre trailers strengthening three-car formations to four or five cars during peak periods or special events. Early strengthening employed converted Hawksworth coaches in matching BR green, later supplemented by Metropolitan-Cammell centre trailers borrowed from Class 115/116 allocations. These composite formations create visual interest whilst accurately representing prototype practice during periods of traffic growth exceeding base fleet capacity.
Train lengths should reflect the class's 600hp power output and typical suburban/secondary passenger loadings. Standard service employed three-car formations, occasionally strengthened to four cars during peaks or special events, rarely exceeding five vehicles. Attempting to depict six or seven-car formations would prove prototypically inaccurate—the class lacked sufficient power for such loadings on any but the flattest routes, and platforms on typical branch and suburban stations couldn't accommodate trains exceeding four or five vehicles.
Sound-equipped models benefit from careful attention to the Class 117's distinctive operational characteristics. The Leyland horizontal engines produced a characteristic mechanical sound quite different from the more common vertical engines fitted to many DMU classes. The four-speed epicyclic transmission created distinctive acceleration patterns with clearly audible gear changes during run-up from station stops. Programming sound decoders to emphasise these characteristics through appropriate volume levels, timing sequences, and sound file selection creates authentic atmosphere that enhances operational sessions.
Multiple unit operation provides fascinating possibilities. The Blue Square coupling code enabled Class 117s to work alongside approximately 84% of first-generation DMU types, creating mixed formations combining different classes. Models can authentically represent Class 117+121 combinations (common on Thames Valley services), Class 117+115/116 pairings (Birmingham Cross-City), and Class 117+Class 117 strengthening (double three-car sets for peak services or special events). These mixed consists create visual interest whilst remaining prototypically accurate.
Depot scenes offer excellent static display opportunities whilst demonstrating maintenance infrastructure. Model a section of Reading, Southall, Tyseley, or Haymarket depot featuring fuelling points, wheel-cleaning equipment, maintenance workshops with inspection pits, parts storage facilities, and crew signing-on points. Include Class 117s alongside other period-appropriate traction—Class 31/37/47 diesels for locomotive-hauled services, other first-generation DMUs, and support vehicles including diesel shunters and engineers' units. Depot staff figures add life—fitters performing maintenance, cleaners washing units, drivers conducting pre-service examinations, and supervisors overseeing operations.
Timetable construction should incorporate the intensive frequency characterising suburban operation. Multiple units working a route in sequence with tight turnaround times at terminal stations, carefully coordinated passing movements at intermediate loops enabling bi-directional service, and systematic coverage of all stations throughout the operating day creates engaging sessions with constant activity. Include operational realism such as units running light engine to commence service diagrams, empty stock movements to and from carriage sidings, and occasional locomotive-hauled trains using the same infrastructure creating operational conflicts requiring careful regulation.
Station operations benefit from attention to period-appropriate details. Include platform staff checking tickets, passengers waiting in covered shelters or open platform areas depending on station facilities, luggage trolleys for passengers with significant baggage, station nameplates in corporate style matching the period modelled, and appropriate advertising posters promoting BR services, local businesses, and government information campaigns. Sound effects including station announcements, departure whistles, and platform activity enhance immersion during operating sessions.
Finally
The British Rail Class 117 represents far more than 123 diesel multiple unit vehicles serving forty years on British Railways; these units embodied the transformation of suburban passenger transport from steam-hauled compartment stock to modern diesel traction offering frequent, reliable, comfortable service. The Pressed Steel Company's elegant construction combined Derby Lightweight engineering philosophy with thoughtful enhancements including toilet facilities and comprehensive passenger amenities, delivering units that remained competitive against increasingly sophisticated successors for decades beyond their anticipated service lives.
For railway historians, the class provides fascinating insights into the practical realities of first-generation dieselisation and British Railways' systematic approach to fleet standardisation. The extensive service spanning four regions—Western, London Midland, Scottish, and Southern—demonstrated the operational flexibility built into British Railways' diesel multiple unit programme, with standardised designs capable of seamless transfer between different traffic patterns and infrastructure characteristics subject only to route knowledge training and basic technical familiarisation.
The remarkable preservation success—51 surviving vehicles spread across twenty heritage locations—represents one of British railway preservation's most significant achievements. The timing of final withdrawals during 2000, well into the preservation movement's maturity, enabled systematic acquisition rather than opportunistic rescues. The flagship Swanage Railway mainline-certified set demonstrates preservation's evolution beyond static display toward active operational railway service, with heritage DMUs contributing genuine transport whilst showcasing historic traction to contemporary passengers.
This makes Bachmann's exceptional OO gauge range and Heljan's comprehensive O gauge collection particularly valuable. These models provide unprecedented access to authentic Class 117 representation with detail quality and technical sophistication matching or exceeding contemporary brass imports whilst remaining accessible to enthusiasts through ready-to-run convenience. The multiple livery variants spanning BR green through Network SouthEast enable authentic layout representation across five decades of British railway evolution, whilst sound-equipped versions deliver immersive operational experiences previously impossible with analog mechanisms.
Model railway enthusiasts incorporating Class 117s into suburban and secondary passenger layouts gain versatile traction ideally suited for authentic British Railways atmosphere. The class's moderate size suits layouts of all scales, the intensive suburban operation provides engaging operational scenarios with frequent train movements and complex timetabling, and the variety of liveries and period-specific modifications offers endless possibilities for authentic recreation. Whether representing Thames Valley services from London Paddington, Birmingham Cross-City metro operations, Scottish Fife Circle duties, or Cornish branch workings, these models bring character and authenticity to any BR-era layout.
As the railway preservation movement continues evolving and new generations discover the fascination of first-generation diesel multiple unit operation, the British Rail Class 117 stands as the perfect exemplar of an era when standardisation, systematic maintenance, and thoughtful design delivered remarkable results. These units prove that engineering excellence emerges not from raw power or technological complexity, but from careful design precisely matched to operational requirements and sustained through disciplined maintenance practice extending service lives far beyond original anticipations.
The Class 117 legacy extends beyond preserved examples and model railway representations. The fundamental design principles validated through forty years of reliable service—comfortable passenger accommodation with essential amenities, reliable moderate-power engines requiring manageable maintenance, flexible formation capabilities enabling traffic adaptation, and robust construction supporting extended service lives—informed subsequent generations of British diesel multiple units. The evolutionary path from Class 117 through Classes 150/153/155/156 to contemporary units maintains recognisable lineage, with each generation refining concepts pioneered by Derby Lightweight designs of the 1950s.
For contemporary observers, the British Rail Class 117 offers perspective on railway evolution and the enduring value of thoughtful design. In an era dominated by increasingly sophisticated technology and ever-shorter product lifecycles, these units' forty-year service careers demonstrate that well-engineered simplicity often delivers better long-term value than cutting-edge complexity. The preservation movement's dedication to maintaining operational examples ensures future generations can experience first-generation DMU travel, understanding the significant transformation these units represented from steam-hauled compartment stock whilst appreciating the comfort and convenience that modern passengers take for granted.
Frequently Asked Questions
How many British Rail Class 117 vehicles were built and when?
The Pressed Steel Company constructed 123 Class 117 vehicles between 1959 and 1961, comprising 42 Driving Motor Brake Second (DMBS) vehicles numbered 51332-51373, 39 Trailer Composite with Lavatory (TCL) vehicles numbered 59484-59522, and 42 Driving Motor Second (DMS) vehicles numbered 51374-51415. This vehicle allocation provided thirty-nine complete three-car sets plus three spare pairs of driving motors for maintenance cover and operational flexibility.
What made the Class 117 different from the similar Class 116?
Class 117s featured distinctive four-character roof-mounted headcode boxes for route identification (Class 116 used simpler disc codes on cab fronts), toilet facilities in the centre TCL vehicle essential for longer-distance suburban services, and slightly different body proportions with deeper windscreens. The Class 117 was specifically designed for Thames Valley services from London Paddington requiring passenger amenities beyond basic suburban commuter routes, whilst Class 116 served shorter-range operations where toilet facilities were unnecessary.
What engines powered the Class 117 DMUs?
Each driving motor vehicle housed two Leyland 680 horizontal six-cylinder diesel engines, each producing 150hp at 1,800rpm for total output of 300hp per power car and 600hp per complete three-car unit. The engines drove through R14 four-speed epicyclic gearboxes with F239 final drive units, providing reliable mechanical transmission well-suited to intensive stop-start suburban operation with frequent station calls requiring rapid acceleration and smooth power delivery.
Why were gangways added to Class 117s after initial service?
Original 1959-1965 units operated without gangway connections, featuring solid end panels suitable for fixed formations serving intensive suburban services where passenger circulation between vehicles proved unnecessary. The comprehensive gangway modification programme between 1965 and 1972 installed corridor connections at all vehicle interfaces, enabling passengers to access toilet facilities regardless of boarding location, improving perceived spaciousness, and permitting flexible strengthening with additional centre trailers during peak periods or special events requiring increased capacity.
Where did Class 117 DMUs typically operate?
Initial allocations concentrated on Western Region Thames Valley services from London Paddington to Reading, Oxford, Maidenhead, and surrounding communities. Geographic deployment progressively expanded to Bristol, Cardiff, Plymouth, Birmingham Cross-City metro operations, Edinburgh Scottish Fife Circle services, Gospel Oak-Barking London services, and Cornish branches including Looe and St Ives lines. This national distribution across four BR regions demonstrated the class's operational versatility and British Railways' systematic standardisation approach enabling seamless inter-regional transfers.
Are any Class 117 DMUs preserved today?
Yes, 51 vehicles survive across more than twenty heritage locations throughout England, Scotland, and Wales, making Class 117 the largest preserved first-generation DMU class. The Swanage Railway operates a mainline-certified three-car set working scheduled Wareham shuttle services on the national network. Other significant holdings include Bo'ness & Kinneil Railway (set L425), Epping Ongar Railway, Strathspey Railway, Great Central Railway, Gwili Railway, and Gloucestershire Warwickshire Railway, with multiple sites offering regular operational services enabling authentic first-generation DMU travel experiences.
What OO gauge Class 117 models are currently available?
Bachmann Branchline produces comprehensive OO gauge Class 117 three-car sets across multiple livery variants: 35-503 BR green with small yellow panels, 35-504 BR blue set L412, 35-505 Regional Railways livery set 117308, plus earlier releases including 35-500 BR green speed whiskers (now sold out), 35-501 BR blue-grey, 35-502 Network SouthEast revised, and 35-500Z GW150 chocolate and cream Kernow exclusive. Standard DCC Ready sets retail at £459.95, Sound Fitted versions at £569.95, featuring dual motors, comprehensive detail, and authentic liveries.
Are Class 117 models available in O gauge or N gauge?
Heljan produces O gauge Class 117 models with deliveries scheduled for December 2025, offering both two-car sets at £699 RRP (approximately £594 discounted) and three-car sets at £1,049 RRP (approximately £891 discounted) across multiple liveries including BR green, BR blue, blue-grey, and Network SouthEast. Unfortunately, no N gauge ready-to-run Class 117 models exist from any manufacturer including Graham Farish or Dapol, representing a significant gap for N gauge modellers seeking first-generation DMU representation.
What coaching stock should I use with Class 117 models?
Standard operation employed three-car Class 117 formations without additional vehicles, occasionally strengthened to four or five cars during peak periods using converted Hawksworth centre trailers in early years or Metropolitan-Cammell centre cars borrowed from Class 115/116 allocations in later periods. Mixed multiple unit operations proved common, with Class 117s working alongside Class 121 single railcars on Thames Valley services, Class 115/116 units on Birmingham Cross-City routes, and other Blue Square coupling code compatible first-generation DMUs across various regions.
Did the Class 117 operate in multiple with other DMU classes?
Yes, the Blue Square multiple working code enabled Class 117s to operate alongside approximately 84% of first-generation DMU types including Classes 115, 116, 118, and 121. Common combinations included Class 117+121 pairings on Thames Valley services providing flexible capacity, Class 117+115/116 formations on Birmingham Cross-City metro routes during peak periods, and double Class 117 three-car sets for special events or heavy traffic loadings requiring six-car formations exceeding standard three-car capacity.
How long did the Class 117 remain in service?
The service span totalled an extraordinary forty years from 1959 initial deliveries until final Silverlink Metro withdrawal in 2000. Major withdrawal programmes occurred as replacement stock arrived: Thames Valley services ended November 1992 with Class 165 introduction, Birmingham Cross-City withdrew September 1993 following electrification, Scottish allocations finished November 1999 when Class 156s arrived, and final Silverlink units operated through 2000 until Class 150 cascades completed replacement programmes.
What liveries did Class 117s carry during their service lives?
The class carried extensive livery variations spanning five decades: original BR green with speed whiskers (1959-1962), BR green with small yellow warning panels (1962-1967), BR green with full yellow ends (late 1960s), all-over BR rail blue (1960s-1970s), BR blue with white-and-blue refurbished stripe (1977-1979), BR blue and grey (1979-1986), Network SouthEast red/blue/white corporate livery with angled or curved lining (1986-1994), and Regional Railways teal and grey provincial livery (1990s), providing excellent variety for model railway representation.
How do Bachmann's Class 117 models perform operationally?
Contemporary reviews praise exceptional smooth running from dual five-pole motors with flywheels driving both power cars through underfloor transmission systems, comprehensive all-wheel electrical pickup ensuring reliable current collection, excellent slow-speed control suitable for realistic station approaches, and sufficient power for typical four-car formations on moderate gradients. Sound-fitted versions receive particular acclaim for authentic Leyland engine recordings, transmission sounds, and 20+ controllable functions creating immersive operational experiences. The only limitation concerns very tight curves below second radius where longer DMU formations may require broader geometry.