The Supermarine Spitfire went into production in 1937, and many variations were made since it was first flown in combat at the very beginning of the war. It was upgraded many times, the Mk1 being the first version. There were 22 variations of the Spitfire, MK 1 through to MK 22.
The Spitfire was the most used British aircraft during the war. Even though the Hurricane scored more kills during the Battle of Britain, the Spitfire is still more famed and credited with the winning of the Battle of Britain. It was first armed with 8 .30 caliber guns, but later was upgraded many times, finally ending up with four 20 MM cannons on the MK 22. The cockpit on the earlier versions had the problem of obstructed rear view, and so the "Teardrop" design made for the P-51 Mustang was adopted and used to solve the problem. The Spitfire definately made the war for Britain, if it was not for the Spit, the war most probably would have been lost.