Reginald Mitchell is most famous for his Spitfire, based on the Supermarine S.6B. The S.6B was a seaplane that competed in the Schneider cup races. It beat everybody else, and based on this construction designed he the Spitfire. Mitchell worked as head-designer at Supermarine Aviation Works. He started as a mechanic in 1921 and worked his way up. The first prototype, Type 300 K5054, flown by the test pilot Mutt Summers, flew first time 5 March 1936. At that time Mitchell was very sick and was sitting in a wheelchair. He died in 1937; 42 years old and he never have to see the Spit in combat action.

The Spit was RAF best fighter in 1940. It was first put into service with the Royal Air Force in 1938. It was modified continuously throughout the war to serve in a variety of roles: fighter (with notable success at high altitudes), fighter-bomber, and photoreconnaissance plane. The version that entered active service in 1938 had a top speed of about 580 km (360 miles) per hour and an armament of eight .303-inch machine guns. The Spitfire XIV, one of the last models of the war, had a ceiling of 12,200 m (40,000 feet) and a top speed of 710 km/t (440 miles per hour). That version shot down more than 300 German V-1 missiles in 1944. During the war, the Spitfire's armament was increased to two 20-millimetre cannons along with two .50-inch machine guns or four .303-inch machine guns. Some Spitfire versions could also carry a 250- or 500-pound (115- or 230-kilogram) bomb under the fuselage and a 250-pound bomb under each wing. The last Spitfires in active service (as photoreconnaissance planes) with the Royal Air Force were retired in 1954. The first 77 Mk is had a two-bladed, fixed-pitch propeller. Subsequent aircraft received three-bladed, two-position airscrews, with fine pitch for take-off and coarse pitch for cruising, and these were subsequently retro-fitted to the earlier aircraft. Taller pilots found the headroom very restrictive and this led to the original flat cockpit canopy being replaced by the bulged version, which was to become a feature of all future marks. Other improvements included the provision of an armour-plated windscreen and 6mm armour panels on the rear engine bulkhead and behind the pilot's seat. Heating for the guns was also installed after it was found that they froze at high altitude. The original armament of eight .303 Browning machine guns had been chosen because of the ready availability of this weapon but, in June 1939, two 20mm Hispano cannon were fitted to L1007 for trails. These proved unsuccessful as the Hispano was designed to be mounted on top of a fighter's engine block, which would be solid enough to absorb the recoil. The mountings in the Spitfire's wings were too flexible causing the guns to jam. Nevertheless, the Hispano was ordered into production, pending a satisfactory solution to this mounting problem.

Before the outbreak of war, considerable interest in buying Spitfires or arranging licence production had been shown by many foreign countries, including Japan. In the event, one example was flown to the French before war dictated that all future production would be earmarked for the RAF. Orders placed before September 1939 amounted to 1,160 to be built by Supermarine with a further 1,000 to be produced by the Nuffield Organization. The symbol of Britain's refusal to give up during that dark summer of 1940, the Spitfire won the hearts of both pilots and public in World War II. By the end of the war, 20.334 Spitfires had been made. 5.665 of them was Spitfire Mk. IX.