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The de Havilland Aircraft Company was a British aircraft manufacturer.
1920 The private company was founded in 1920 when Airco, of which Geoffrey de Havilland had been chief designer, was sold to BSA. De Havilland then set up a company under his name in September that year at Stag Lane Aerodrome in Edgware. It later moved to Hatfield, in Hertfordshire, England. He was neither chairman nor managing director of his company, begrudging all time lost to technical work and feeling exasperated by financial responsibilities.
Images of the Edgware factory are available on the RAF Museum London website.
1924 The De Havilland Aircraft Company, Limited, continued to manufacture the DH 9 and 9A types of military aircraft, the first-named being on occasion fitted with water-landing gear. In addition, on the service side, it produced certain experimental machines for the Air Ministry. On the commercial side, it concentrated chiefly on the DH 50 four-passenger machine, to which we referred in our review a year ago, and took the first steps towards the production of a new type, the DH 54, a sixteen-seater, to be driven by a 650 horse-power Rolls-Royce "Condor " engine. Similar steps have been taken in connection with a three-engined commercial machine.
1925 De Havilland pioneered the light aeroplane movement with the Moth.
1926 Established the Engine Division, producing the Gipsy aero-engine.
1929 Became a public company. Directors were Alan Samuel Butler (Chairman), Geoffrey de Havilland (Technical Director), Charles Clement Walker (Chief Engineer), ]]Francis Trounson Hearle]] (General Manager) and Thomas Piercy Mills (Solicitor).
Initially, de Havilland concentrated on single and two-seat biplanes, essentially continuing the DH line of aircraft built by Airco, but powered by de Havilland's own Gypsy engines. These included the Gypsy and Tiger Moths. These aircraft set many aviation records, many piloted by de Havilland himself. Amy Johnson flew solo from England to Australia in a Gypsy Moth in 1930, the flight taking 19.5 days.
The Moth line of aircraft continued with the more refined (and enclosed) Hornet Moth and Moth Minor, the latter being a low-wing monoplane constructed of wood.
The DH.84 Dragon was the first aircraft purchased by Aer Lingus, who later operated the DH.84B Dragon Express and the DH.89 Dragon Rapide. De Havilland continued to produce high-performance aircraft including the high-speed twin-piston engine DH.88 Comet mail-plane, one of which became famous in its red livery as the winner of the MacRobertson Air Race from England to Australia.
The high-performance designs and wooden construction methods culminated in perhaps the most famous de Havilland aircraft - the Mosquito, constructed primarily of wood because of the shortage of aluminium during the war. The company followed this with the even higher-performing Hornet, which was one of the pioneers of the use of metal-wood and metal-metal bonding techniques.
1933 Constructors of light aeroplanes and low-powered engines. Also operates De Havilland Flying School. Head Office and Works: Stag Lane Aerodrome, Edgware, Middlesex.
1935 Established De Havilland Propellers as a subsidiary company.
1937 Designers and manufacturers of aircraft, aero engines and controllable-pitch airscrews. "Albatross" Aircraft. "Dragonfly" Aircraft. "Gipsy" Aero Engines. "Moth" Aircraft.
1939 See Aircraft Industry Suppliers
1942 Private company.
1944 the Engine Division became the De Havilland Engine Co
After the Second World War, de Havilland continued with leading-edge designs in both the military and civil field, but several public disasters doomed the company as an independent entity. The experimental, tailless, jet-powered de Havilland DH 108 Swallow crashed in the Thames Estuary, killing Geoffrey de Havilland Jr, son of the company's founder.
1952 The de Havilland Comet was put into service as the first commercial jet airliner, twice as fast as previous alternatives and a source of British national pride. The Comet suffered three tragic and high-profile crashes in two years.
1952 Less well known, but equally disastrous, was the explosion of the DH.110 Sea Vixen prototype during the 1952 Farnborough Air Show, which also killed members of the public.
1960 As part of a general consolidation in the aircraft industry, Hawker Siddeley acquired Blackburn Group and de Havilland Holdings, making this one of the 2 large airframe manufacturing groups in Britain
1961 De Havilland Holding Ltd was a subsidiary of Hawker Siddeley. De Havilland Aircraft employed 15,000. Also De Havilland Engines. Makers of DH 121, Comet, Sea Vixen, Vampire, Heron, Dove, Caribou, Otter and beaver aircraft. Also the Gnome, Gyron and Gypsy engines. Employed 35,000 in the group. 
1961 Manufacturers and designers of "De Havilland" aircraft, including "Comet" airlines and "Sea Vixen" naval fighters. 15,000 employees.
1977 Hawker Siddeley incorporated into British Aerospace (BAe). In this period, many designs started by de Havilland came into production, including the Trident, HS-146 (later BAe-146), HS-125 (later BAe-125).
Post 1944 See De Havilland Engine Co.
1911 De Havilland motorcycle being sold at Warwick Road, Coventry
Presumably a product of Geoffrey de Havilland's early interests in automotive engineering when he was living in Rugby.
For De Havilland Aircraft models see De Havilland: Aircraft.