Bristol Aero Engines in 1959) and incorporated it as the Bristol Siddeley division. Bristol Siddeley, with its principal factory at Filton, near Bristol, had a strong base in military engines, including the Olympus, Viper, Pegasus (vectored thrust) and Orpheus. They were also manufacturing the Olympus 593 Mk610 to be used in Concorde in collaboration with SNECMA. They also had a turbofan project with SNECMA. Leavesden Aerodrome, Watford was originally owned by the Ministry of Defence and used during World War II for the manufacture of Mosquito and Halifax aircraft. For a number of years, Rolls-Royce used the site for the manufacture of helicopter engines until the site closed in June 1993. The former Rolls-Royce factory at Watford is now known as the Leavesden Film Studios and has produced world-famous films, including the James Bond, Star Wars and Harry Potter series. RB211—the 1971 receivership and nationalisation The amalgamations and disappearances of the 1950s and 1960s left a small number of major airframe manufacturers based in only a few countries. The competition for the very large contracts to supply their engines grew intense. Expensive research and development became vital. Real profits came from the maintenance contracts which might peak a whole human generation later. By the 1980s it was said that each generation of aero engines cost around 10 times that of its parent. At this time Rolls-Royce employed 80,000 people and it was Britain's 14th largest company in terms of manpower. It was generally known that problems had recently arisen requiring government support of the RB211 programme as one outcome of intense financial competition with Pratt & Whitney and General Electric for the original RB211 contract. In the new year of 1971 financial problems caused largely by development of this new RB211 turbofan engine designed and developed for Lockheed Aircraft Corporation's new L-1011 TriStar led, after several government-provided cash subsidies, to the recognition Rolls-Royce had no resources left and it voluntarily entered receivership 4 February 1971. There were said to have been acrimonious telephone conversations between US president Richard Nixon and the British prime minister Edward Heath but these were subsequently denied. Responding to questions as to how the situation could have arisen the chief executive advised that in their calculations they were guided by the success of their estimates in the launching of their Spey engine. Had the government simply nationalised Rolls-Royce it would have been unable to avoid the