As the new cars were urgently required they were based on existing L Stock.

Several years after construction both types were absorbed into the Q Stock.

Twenty-eight cars were built in 1935 by Birmingham Railway Carriage and Wagon Company: fourteen were driving motor cars and the rest were trailers.

Upon conversion to Q Stock, all the cars were transferred to the District line (with the Hammersmith and City Line services being operated from 1938 onwards by new trains of O Stock).

Twenty-six cars, all trailers, were built in 1935 by Metropolitan Cammell.