The Class 120 was a cross-country DMU in three-car formation, built at the British Rail Swindon Works. Totalling 194 cars, three batches were built:
1958 - 49 sets for the Western Region 1959 - 7 sets for the Scottish Region 1961 - a further 9 sets for the Western Region
Some cars had a trial refurbishment but this was found to be too expensive, meaning an early withdrawal for most of the class. Some of the London Midland Region's units were transferred to Scotland in the mid-1980s, mainly finding use on local services from Edinburgh and the Glasgow and South Western route. The final vehicles survived until 1989. One trailer car survives at the Great Central Railway. This unit formation had a Metro-Cammell centre trailer.
