It is notable for being the first British jet engine to fly, as the "Whittle Supercharger Type W1",[2] powering the Gloster E.28/39 on its maiden flight at RAF Cranwell on 15 May 1941.

After a period of indifference, in June 1939 a demonstration of the Power Jets WU was made before a delegation of the Air Ministry, notably Dr David Pye, Director of Scientific Research.

The demonstration was so successful that the Ministry quickly arranged to buy the engine to give Power Jets working capital, lending it back to them for testing.

[4] Unlike the Whittle WU, that began bench testing in 1937, the W.1 was a symmetrical engine designed to facilitate, after development, installation in an aircraft.

IX, not yet introduced, mounting an experimental engine reached 403 miles per hour (649 km/h) at high altitude.