British Rail Class 121

British Rail Class 121
W55033 at the Colne Valley Railway in original green livery
Specifications
Car length64 ft 6 in (19,660 mm)

Sixteen Class 121 single-car driving motor vehicles were built from 1960, numbered 55020-55035. These were supplemented by ten trailer vehicles, numbered 56280-289 (later renumbered 54280-289). They had a top speed of 70 mph, with slam-doors, and vacuum brakes. The driving motor vehicles were nicknamed "Bubble Cars" by some enthusiasts.