The Mustang, designed by North American Aviation to a British specification, was perfected by fitting the Rolls-Royce Merlin engine. A low-drag wing and fuselage meant that it could fly faster and further than the Spitfire using the same engine.

The US 8th Air Force doctrine of strategic bombing assumed that the heavily armed B-17s and B-24s would be able to defend themselves against fighter attack, but by October 1943 losses were so great that the offensive was suspended. Neither the Spitfire nor the P-47 had the range to escort the bombers deep into Germany. However the P-51 Mustang, fitted with drop tanks, could fly as far as Berlin and even at this range its performance was superior to that of most German fighters.

In February 1944 the offensive was resumed and inthe great air battle which ensued, the P-51 Mustang came into its own. It gave the Allies command of the air over Germany in daylight, and first tied down and then destroyed the Luftwaffe over its home territory. This gave the tactical air forces the air supremacy they needed to ensure the success of the final land campaign which began with the invasion of Normandy in June 1944.

The P-51 on display is a replica painted as an aircraft of the Duxford-based 78th Fighter Group. Numerous airworthy P-51s are based at Duxford and regularly take to the air over the historic airfield.