Class 101 Met-Camm 2,3 & 4-car DMUs

Introduced: 1956
Coupling code: Blue Square
Underframe: 57ft 6in
Engines: AEC 150hp (Class 101) or Leyland 150hp (Class 102)
Transmission: Mechanical

One of the most numerous and widely used types, the 620 vehicles were built for the North Eastern (134 sets - 347 vehicles), London Midland (48 sets - 114 vehicles) and Scottish (63 sets - 159 vehicles) Regions. They later spread to the Eastern and Western Regions and ran onto the Southern Region.

They were updated version of the earlier Yellow Diamond Met-Camm Lightweights with the blue square control system. Including those early types and the more powerful Rolls-Royce engined variants later (Class 111s) a total of 760 Met-Camm vehicles were built.

When class numbers were introduced the power cars were initially divided into Class 101s (the vehicles with AEC engines) and Class 102s (those with Leyland engines). Later the classes were rationalised with all becoming Class 101s.

The type was used as the testbed for refurbishment scheme in the 1970s, which led to many types being given a life-extension at a time when BR had no replacements for the ageing vehicles.

Many sets were given an additional "facelift" to see them become one of the last types to be phased out of traffic in the early years of the 2000s, only surpassed by some bubble cars returned to traffic.

Many vehicles saw further use as parcel, sandite and route learning units and many entered preservation.