 It was possible to operate a 3-car train, but in order to do so, a shorting plug had to be fitted to the control trailer, to connect the lighting circuits, and to complete the door interlock circuit.The cars were initially used on the Piccadilly tube.The trailer cars were numbered 800-819, the converted motor cars were 480-499, and the control trailers were initially 700-719, but were renumbered to 1700-1719 in 1926.