British Rail Class 123
The BR Class 123 was a small fleet of four-car diesel multiple unit sets built in 1963 by BR Swindon Works for Western Region cross-country express services. Marketed under the InterCity brand name — one of the earliest uses of that now-ubiquitous term — the ten sets were designed to provide fast, comfortable services on routes where locomotive-hauled coaching stock would be excessive but where the standard first-generation suburban DMUs were inadequate in terms of speed and comfort.
The Class 123 was powered by two Albion EN250 diesel engines per power car, giving a significantly higher power-to-weight ratio than the contemporary suburban DMUs and enabling a maximum speed of 90 mph. The sets were built to a high specification, with more generous seating, better soundproofing, and a more refined interior than the standard first-generation DMU — reflecting their express rather than suburban role. The four-car formation consisted of two driving motor brake seconds and two trailer seconds.
The ten sets worked Western Region cross-country expresses throughout the 1960s and 1970s, providing InterCity-quality service on routes including Cardiff to Portsmouth and similar cross-country workings. They were withdrawn in 1984 as High Speed Trains and locomotive-hauled Mark 3 coaching stock progressively took over the Western Region's express services. None was preserved.
Design and development
Swindon Works built the Class 123 to a higher specification than standard first-generation DMUs, using the more powerful Albion EN250 engine to achieve 90 mph capability. The sets were among the first BR rolling stock marketed as 'InterCity', reflecting their intended role on express rather than suburban services.
Service and withdrawals
The Class 123s worked Western Region cross-country expresses from 1963. As HSTs and locomotive-hauled Mark 3 sets progressively displaced them from express duties in the late 1970s and early 1980s, the Class 123s were cascaded to secondary workings before final withdrawal in 1984. None was preserved.
Identification features
Four-car DMU with Albion engines, 90 mph capable.
Notable locomotives
- None preserved
Allocations and regions
Allocated to Western Region depots for cross-country express workings, including Cardiff to Portsmouth and similar inter-regional services.
