were transferred to the now defunct Hawker Siddeley Canada. Postwar In 1948, the company name was changed to Hawker Siddeley Group. The aircraft division became Hawker Siddeley Aviation (HSA) and the guided missile and space technology operations as Hawker Siddeley Dynamics (HSD). In 1959, the aero engine business, Armstrong Siddeley was merged with that of the Bristol Aero Engines to form Bristol Siddeley. In the late 1950s, the British government decided that with the decreasing number of aircraft contracts being offered, it was better to merge the existing companies, of which there were about 15 surviving at this point, into several much larger firms. Out of this decision, came the "order" that all future contracts being offered had to include agreements to merge companies. In 1959, Folland Aircraft was acquired, followed by de Havilland Aircraft Company and Blackburn Aircraft in 1960. In 1963, the names of the constituent companies were dropped, with products being rebranded as "Hawker Siddeley" or "HS". In this period, the company developed the first operational, and, by far, the most successful VTOL jet aircraft, the Harrier family. This aircraft remained in production into the 1990s and remains in service. Hawker Siddeley Nuclear Power Company The Hawker Siddeley Nuclear Power Company built and operated the 10 kW JASON reactor in Langley, Berkshire (then in Buckinghamshire). The reactor was in operation there from 1959 to 1962 and generated a total of 1.4 MWh before being shut down and transported to the Royal Naval College in Greenwich, London. Kingston headquarters and factory In 1948, Hawker Siddeley acquired a factory in Kingston upon Thames, Surrey, on the Richmond Road near Ham. This was to become their main aircraft factory and headquarters. Expansion into railways In 1957, Hawker Siddeley purchased the Brush group of companies that included Brush Electrical Machines, and Brush Traction, which manufactures electromotive equipment and railway locomotives. The Brush prototype locomotives Falcon, and the futuristic but over-weight HS4000 'Kestrel', were produced there. Other railway engineering assets were acquired, including Westinghouse Brake & Signal and the engine builder Mirrlees Blackstone, which came with the Brush businesses. In the early 1970s, Hawker Siddeley's Canada Car and Foundry subsidiary began to build rapid transit vehicles for the North American market. The first order was for the Port Authority Trans-Hudson line and consisted of 46 PA-3 cars numbers 724–769, which were largely based on the original hexagonal profile PA-1 & PA-2 cars