The Westland Whirlwind emanated from an Air Ministry Specification of 1935 calling for a single-seat day/night fighter armed with 4 cannon. Of the six companies that responded, Supermarine, Boulton Paul and Westland were initially chosen to produce prototypes. A contract for two Westland prototypes was placed in February 1937 and associated work began, but neither Supermarine nor Boulton-Paul were able to proceed at that time. An order was finally placed with these 2 companies in December 1937 but cancelled the following month in recognition of Westland being well advanced.
The first prototype Whirlwind took to the air on 11 October 1938. Powered by two Peregrine 885 hp engines, it exhibited very good handling characteristics. However, modifications were required that delayed development and it was not until January 1939 that a production order was placed for 200 machines.
No 25 Squadron at RAF North Weald was destined to be the first Whirlwind unit and received three machines in May/June 1940. However, with very slow aircraft delivery in prospect, it was decided to re-equip 25 Squadron with the Bristol Beaufighter and that No 263 should now become the first operational unit. Problems in production resulted in this squadron not becoming operational with the Whirlwind until December 1940. In September 1941, No 137 Squadron became the second Whirlwind unit and it was shortly thereafter in January 1942 that, with the realisation that the Beaufighter was just as good as if not better as a night fighter, production ceased. The two squadrons continued to conduct bomber escort missions until the summer of 1942 when, the aircraft’s role was changed. Racks to carry 2 x 250 lb or 500 lb bombs were fitted to supplement the 4 x 20 mm cannon and the Whirlwind was thereafter employed on Rhubarb missions and anti-shipping sorties.
The final Whirlwind mission to be flown by 137 Squadron took place in June1943 and that by 263 Squadron in December of that year – the units re-equipping with Hurricane Mk IVs and Typhoons respectively. On 1st January 1944 the Whirlwind was officially declared obsolete.
A total of only 116 Whirlwinds were built and there are no known survivors.