Squadron leader John Douglas Derry DFC (5 December 1921 – 6 September 1952) was a British test pilot who is believed to be the first Briton to have exceeded the speed of sound in flight.

His operational career began late in 1944 when he joined 182 Squadron, flying Hawker Typhoons on close support to the Allied armies in the Low Countries.

[citation needed] Despite lack of substantial evidence (the recording apparatus was switched off during the flight), the news was promoted by the British press as having broken the sound barrier.

Derry was killed in the 1952 Farnborough Airshow DH.110 crash (the DH 110 went on to become the de Havilland Sea Vixen) when his aircraft broke up because of a design fault resulting in catastrophic structural failure, with 31 fatalities including himself, his flight observer Tony Richards, and 29 spectators.

John Justin plays Philip Peel, a test pilot who brings his plane through the sound barrier and out of the speed-creating dive by the untried technique of applying reverse direction to the control column.