 The British Transport Commission approved the project "in principle" in 1950, and a design contract was awarded to Metro-Cammell.A mock-up of a car body was constructed at Acton Works, and included some features which had been tried out on individual cars of 1938 stock, including some circular windows, and others that ran up above the roof line, to give passengers better visibility at stations.It was originally called 1951 Stock and then 1952 Stock when the programme was delayed.