At the start of the Second World War the de Havilland company was building Tiger Moths, Rapides and Airspeed Oxfords for the RAF. In addition all other aircraft completed were requisitioned for use as transports or training aircraft. In 1940 de Havilland acquired the Airspeed company and the design offices were merged.
Although none of de Havilland's warplane designs of the 1920s and 1930s had been successful the company proposed a wooden, high-speed bomber, trading defensive armament for speed. The Air Ministry doubted the ability of the company to produce such a machine, but support came from Sir Wilfred Freeman, Air Council Member for Research, Development & Production.
The design group moved from Hatfield to Salisbury Hall, near St Albans , and began detailed work under the supervision of Bishop. The prototype was built in great secrecy and when completed taken to Hatfield for its maiden flight. The Mosquito was first flown by Geoffrey de Havilland junior on 25 November 1940 and entered RAF service in 1941.
Its first use was for photographic reconnaissance but eventually it saw service as an airliner, day fighter, night fighter, intruder, anti-shipping fighter, bomber and target tug. It was one of the safest, fastest and most versatile aircraft of the war. Its production so dominated Hatfield that all other work was transferred to sub-contractors. Morris Motors produced Tiger Moths at its Cowley car factory near Oxford and Rapide production was transferred to Brush Coachworks at Loughborough, Leicestershire. Even so capacity at Hatfield was limited. A second Mosquito assembly line was established at Leavesden, Hertfordshire, with the first being delivered in May 1942. Mosquitos were also built by Standard Motors at Coventry , Percival Aircraft at Luton , Bedfordshire, and Airspeed at Christchurch , Hampshire.
Although the de Havilland company concentrated its efforts on the Mosquito, constantly improving it, new designs continued to be worked up. None, however, saw service until after 1945.
During World War Two the jet engine was developed in great secrecy by Frank Whittle. Geoffrey de Havilland and Frank Halford were among a select group invited to see the first aircraft to which it was fitted, the Gloster E.28/39, fly at RAF Cranwell, Lincolnshire . The aircraft had been designed by a former DH designer, George Carter. Halford was enthusiastic about the new engine and began work on one for the de Havilland Engine Co while Bishop began work on a new aircraft.
The Rover Car Company had been given the contract to produce jet engines at Barnoldswick, Lancashire , for the Gloster Meteor. There were problems with these engines, however, and so the Meteor made its first flight on 5 March 1943 powered by two Halford H.1 jet engines. This engine was developed to form the Goblin.
On 29 September 1943 the DH.100, powered by the Goblin, was flown for the first time by Geoffrey de Havilland Jnr. It was originally known as the Spidercrab but was renamed Vampire. Production was contracted to English Electric at Preston , Lancashire , and the first production aircraft flew on 20 April 1945 . It did not enter service, however, until after the war.
In July 1944 Geoffrey de Havilland Jnr flew the Hornet for the first time. It was a small single-seat, twin-engined fighter of composite wood and metal construction for use in the Far East . Its performance was outstanding and production began late in 1944, but it did not enter service before the end of the war.