Several railway companies experimented with diesel traction between the wars, testing shunting engines, 4-wheel 'railbus' units and bogie rail cars. Only the Great Western with AEC developed 'prototypes' into viable production trains. Following the smooth-curved coach-built express railcars Swindon produced a more angular streamlined styling, better suited to mass production and built 20 cars to this design, including one parcels car and notably 4 single-ended cars arranged to work in pairs. These last four being the forerunners in mechnical design of the British Rail diesel multiple units of the 1950/60s.
Era 3.