The British Rail Class 100 refers to a group of first‑generation diesel multiple units (DMUs) constructed for British Railways in the mid‑1950s. Built by the Gloucester Railway Carriage & Wagon Company (Gloucester RCW) between 1956 and 1958, these units were part of the postwar modernization programme that replaced steam on many local and regional passenger services.

Design and characteristics

Class 100 trains were self‑contained diesel multiple units with underfloor engines and driving cabs at each end of a set. They were intended for short to medium distance services, providing frequent stop capability and quicker turnaround than locomotive‑hauled trains. Externally they followed the compact, utilitarian styling common to first‑generation DMUs and were built using contemporary carriage construction techniques.

Operation and formation

Most Class 100 vehicles were arranged in two‑car sets that could operate singly or be coupled to form longer trains. Interiors were basic but practical, with compartment and/or open seating layouts typical of the era. Their operating duties included suburban, branch line and rural services across various regions of the British Rail network.

Service history and withdrawal

Introduced in 1956–58, Class 100 units served through the 1960s and 1970s. As newer DMU designs and refurbished rolling stock became available, many first‑generation units were progressively withdrawn. By the late 1970s and into the 1980s most Class 100 vehicles had been retired from mainline service.

Preservation and legacy

A number of Class 100 vehicles have survived into preservation and can be found on heritage railways where they operate for special events and enthusiast services. They are valued for representing early diesel multiple unit development and for illustrating the transition from steam to diesel traction.

Notable facts

  • Built by Gloucester RCW in collaboration with industry partners during 1956–58.
  • Typically formed as two‑car sets, adaptable to longer formations for peak services.
  • Several vehicles preserved; these appear at heritage railways and in railway collections.

For additional technical details and historical records, see contemporary sources such as British Rail Class 100 and manufacturer histories like Gloucester RCW.