W4050

De Havilland's design team built E0234 in secret in a hangar beside Salisbury Hall, London Colney. It went by road to Hatfield in November 1940 and was rolled out in yellow on 19 November. Geoffrey de Havilland Jr made the first flight on 25 November 1940, with engine installation designer John Walker aboard.

A demonstration to Lord Beaverbrook and other ministers on 29 December 1940 led to an order for 150 aircraft. Renumbered W4050, the prototype reached 22,000 ft on 17 January 1941 and outran a Spitfire in trials. At Boscombe Down on 24 February 1941 its tailwheel jammed while taxiing and the fuselage cracked by the starboard hatch. It received the fuselage built for the second prototype, W4051.

W4050 stayed with de Havilland as a trials aircraft for engines, armament and new versions. Fitted with two-stage supercharged Merlins it reached 437 mph. After tests in December 1943 it was grounded for good, then used for instruction and stored at Hatfield. The firm's PR chief, Bill Baird, is said to have resisted calls to burn it.

Walter Goldsmith, owner of Salisbury Hall, took it back in 1958-59 as the first exhibit of what became the Mosquito Aircraft Museum. A conservation programme began after 2001, backed by BAE Systems and the Heritage Lottery Fund. It was finished in December 2015, 75 years after the first flight.

In the Walter Goldsmith Hangar alongside the museum's other two Mosquitos on the Salisbury Hall site where it was built. It is in its original prototype yellow.