They were built with automatic plug doors, which initially caused some concern as additional time and resources were required to perfect them. The design was later used on the Class 442 "Wessex Electrics". Most of the fleet was air-conditioned, except for a small number of coaches built as outer-suburban stock, which ran in push-pull configuration. A number of coaches were first class, and there were several dining cars and five driving van trailers (DVTs) that included passenger seating. There were also a number of accompanying generator vans to supply power.