During the late 1940s and early 1950, British Overseas Airways Corporation (BOAC) flew their Lockheed Constellations and Boeing Stratocruisers into Filton to be serviced in the newly completed Brabazon Hangar, then the largest hangar in the world. Maintenance flights to Filton ceased when suitable hangars were completed at London Heathrow Airport. In 1954, BAC opened a technical college for apprentices and trainees at the bottom of Filton Hill. This was eventually absorbed by Filton Technical College, that had opened on the opposite side of Filton Avenue in 1961. In 1958, the aero engine interests of the Bristol Aeroplane Company and Armstrong Siddeley were amalgamated to form Bristol Siddeley Engines. Rolls-Royce purchased Bristol Siddeley Engines in 1966. On 4 February 1971, Rolls-Royce were declared bankrupt due to the burden of development of the RB211 engine for the Lockheed L-1011 Tristar jetliner. Due to the importance of Rolls-Royce engine division to the Royal Air Force, the Government nationalised the company. Frederick Corfield the then local MP, was then Minister for Aviation, and presumably had influence over what was an unusual decision for a Conservative administration.