Class 123 (BR Swindon Intercity Services 4-car)

The Class 123 was the last type of first generation diesel multiple unit to enter service and in many ways the best, being designed for longer inter city routes with a high degree of passenger comfort including some corridor compartments and B4/B5 bogies which gave a better ride at higher speeds [1]. They had a similar front-end design to the Class 309 EMU with wrap around cab windows [2].

Number built: 40 (10 4-car sets)
Built: 1963
Builder: BR Swindon
Engine: 2 BUT (Leyland Albion) 6-cyl per power car
Power: 920 hp (686 kW)
Formation: Driving Motor Brake Standard Lavatory (DMBSL)+
Trailer Composite Corridor (TCK)+Trailer Standard Lavatory or
Trailer Buffet Standard (TSL/TSLRB)+
Driving Motor Standard Corridor (DMSK)

The Class 123 was also fitted with Pullman style gangways to the cab ends so everyone on a train could access the buffet car. They were used on South Coast-Wales services though were based on Western Region as Southern Region did not want to have anything to do with diesel-mechanical units! They were later used on outer-suburban services out of London Paddington [3].

They were surplus to requirements by the late 1970s but had a short reprieve in the North East of England before finally being withdrawn in 1984.
Class 123 at Swindon (KD Collection)

[1] Brian Haresnape, Diesel-Multiple Units: The First Generation (Ian Allan, 1985) p. 71
[2] David Lawrence, British Rail Designed 1948-97 (Ian Allan, 2016) p. 135
[3] Colin J Marsden, DMU and EMU Recognition Guide (Ian Allan, 2013) p. 83