As WWII became increasingly likely the Royal Air Force determined that it was deficient in a powerfully armed aircraft that could undertake long-range escort duties and night-fighter operations. A requirement not all that different from the German's Messerschmitt Bf-110. From a specification drawn up in 1937 came the Westland Whirlwind, a heavily armed escort fighter. It had some teething problems related to the Rolls Royce Peregrine engine and the fact that it's landing speed was 80 mph, which meant that it could not use the standard grass field of a British aerodrome. The long, slender nose of the Whirlwind was at odds with the powerful armament of four 20-mm cannons. It showed some promise in combat, however, like its German counterpart it was not agile enough to successfully combat enemy fighters.
After some deliberation the RAF purchased only 112 and equipped only two squadrons, No.s 137 and 263, with the aircraft. After initial use as an escort fighter, it was relegated to convoy patrols and eventually as a "Whirlybomber" flying low-level "rhubarbs" with bombs and cannons against targets of opportunity in France. It was phased out of use in 1942 as better aircraft (primarily the Typhoon and Beaufighter) were being put into service that would outperform it at a lower cost. The Typhoon could carry the same armament with a single engine, and the Beaufighter was even more powerfully armed and used Bristol radial engines that were in greater supply. Also, Rolls Royce dropped the Peregine engine to focus on producing the Merlin series of engine.
The Whirlwind was a single seat, twin engined fighter powered by a pair of Rolls Royce Peregrine I engines. They each generated 885 hp and could move the Whirlwind up to 360 mph. The range was about 800 miles with a ceiling of 30,000 feet.
It was powerfully armed with four 20-mm Hispano Mk I cannons in the nose with 60 rounds per gun and could carry up to 1000 lbs of bombs on two underwing racks.