In April 1940, the British Government was seeking to quickly increase the RAF’s fighter strength and approached North American Aviation with a view to having the company build Curtiss P-40 Tomahawks under licence. North American came back with the proposal to design a new fighter powered by the same Allison engine used by the Tomahawk and this was agreed with the stipulation that a prototype should be available within 120 days. This deadline was duly achieved and, on 26th October 1940 the resulting aircraft, designated the NA-73X, took to the air for the first time. It was an immediate success and a first production contract was awarded for 320 machines, to be named by the RAF as the Mustang Mk1 – with a further 150 being ordered under the lend-lease programme. The aircraft was designated the P-51A Apache by the USAAC.
The Mustang entered service with the RAF in 1941 and first saw combat in May 1942. Owing to a relatively poor performance above 15,000 ft it was employed initially on reconnaissance and ground attack duties rather than as a fighter. However, when re-equipped with the Merlin 61 engine, the machine proved to enjoy an excellent high level performance. The now USAAF took up the initiative with development of the P-51B using a Packard Merlin and various other enhancements; these improvements enabled the aircraft, now known universally as the Mustang, to be introduced as a bomber escort and it was largely due to the American machines that daylight raids deep into Germany became possible in late 1943 without incurring unacceptable bomber losses. Given the P-51’s armament of 6 x .5in machine guns together with the capability to carry a bomb load of 2,000 lbs and 10 x 5in rocket projectiles, additional roles from early 1944 included operations against Luftwaffe airfields and lines of communications. Meanwhile, the RAF machines were used extensively to seek out V1 sites and on interdiction operations. By VE day, the USAAF P-51 groups in the European Theatre claimed to have shot down 4,950 enemy aircraft with a further 4,131 destroyed on the ground.
A total of 16,766 Mustangs were built. The aircraft continued in USAAF service after the 2nd World War and also served in the air arms of no fewer than 55 nations. Scores of airworthy P-51s still exist worldwide with many in private ownership.
RAF Mustangs were based at Tangmere’s Advanced Landing Grounds in 1944 and units frequently operated from the airfield itself.