On 1 July 1933 the District Railway amalgamated with other Underground railways, tramway companies and bus operators to form the London Passenger Transport Board, and from 23 October 1933 Piccadilly line trains ran through to Uxbridge and the District line shuttle was withdrawn. Most of the trailer cars on the District line were the 1904–1905 B Stock type with wooden bodies, but motor cars were less than fifteen years old. The 1935–1940 New Works Programme saw the Q Stock formed from these motor cars, upgraded with electro-pneumatic brakes and guard controlled air-operated doors, and the trailers replaced with new vehicles. The off-peak District line services on the Hounslow branch were withdrawn on 29 April 1935 and South Acton served by a shuttle to Acton Town.