Geoffrey de Havilland built his first (unsuccessful) aircraft in 1909. His second, flown in 1910, was bought by the War Office, and de Havilland was taken on as designer at the Balloon Factory (later Royal Aircraft Factory), where between 1911 and 1914 he designed the F.E.2, S.E.1, S.E.2, B.E.1, and B.E.2. In 1914 he joined the Aircraft Manufacturing Company at Hendon, designing the D.H.2 pusher fighter, D.H.3, and D.H.10 twin-engined bombers, D.H.5 fighter, and D.H.4 day bomber. The latter was extensively built in the USA. The D.H.9 and 9a were variations; the 9a equipped post-war RAF bomber squadrons and it, too, was built in the U.S.A.. Nearly 3,000 were constructed in Russia as the R-1.
During 1920 the Aircraft Manufacturing Company, which had been building de Havilland designs, was re-formed as the de Havilland Aircraft Company Ltd.
The first aeroplane built at Stag Lane was the DH.18.
The D.H.53 Humming Bird ultralight was the best entrant in the 1923 Air Ministry Light Aeroplane competition, but de Havilland realised that their passion for lightness was an error, and in 1925 produced the first Moth to more sensible proportions. It was sold all over the world. A number of cabin monoplanes and a military version, the Tiger Moth, followed; over 8,000 Tigers were built for various air forces.
The three-engined D.H.66 Hercules was flown by Imperial Airways from 1926, and in the 1930s many domestic and foreign airlines used the twin-engined D.H.84/89 Dragon/Dragon Rapide and four-engined D.H.86 Express.
In 1934 de Havilland designed the all-wood D.H.88 Comet twin-engined racer for entrants in the "MacRobertson" England-Australia race. At a fixed unit price of GBP5,000 this gamble paid off; three were entered, and one of these won the speed prize. By 1939 the firm was producing the D.H.91 Albatross, a fast airliner with four engines; the twin-engined D.H.95 Flamingo feederliner and the diminutive D.H.94 Moth Minor. All production of these ceased at the outbreak of war, which also cut short a promising bombertrainer, the D.H.93 Don. In 1938 work started on a fast unarmed wooden bomber, the D.H.98 Mosquito. It became one of the most versatile aircraft of its time, and by the end of the war a single-seat fighter version attained a speed of 760km/h. The Vampire, de Havilland's first turbojet fighter, Venom, Sea Venom and later Sea Vixen, served for a decade after the war.
The other problem arising from the cancelled Don order was the under-utilisation of woodworking skills at the de Havilland factory. To compensate the Company, on 2nd September 1938 the Air Ministry awarded them orders for a large batch of Tiger Moths, some more Queen Bees, plus a contract to build 150 all wooden Airspeed Oxford trainrs for the RAF. When Geoffrey de Havilland read the letter, he saw red - de Havilland's did build somebody else's aeroplane. de Havilland gave Nixon a simple order - "Buy that company!"
As it transpired, this order took some doing and it would be several years before de Havilland's owned Airspeed Ltd, of Portsmouth. Airspeed joined de Havilland in 1951.
Back in civil work, the company produced the twin-engined Dove, four-engined Heron and, in 1949, the first jet airliner in the world, the D.H.106 Comet. The Comet 1 ran into constructional problems, but the Mark IV achieved success. The last DH designs were the D.H.121 Trident, a three-engined airliner for BEA, and the D.H.125 executive jet (both first flown 1962). Both were still in production in 1978, long after the company's absorbtion into the Hawker Siddeley Group in 1960, and the D.H.125's successors were still in production at the turn of the new century.