The object of this paper is to discuss the evolution of the wartime fighters the Spitfire and Seafire, designed by the Supermarine Works of Vickers–Armstrongs Ltd. In particular, it will be confined to the design and technical side of the problem. The production undertaking, which resulted in the manufacture of over 22,000 of these aircraft in 33 different types, would undoubtedly need a paper of its own.

In order to make the matter clear it is proposed to begin with a brief history of the early development of high speed aircraft by the firm. The next logical step is to survey the Spitfire family as a whole and to trace the relative importance of the different types, giving some indication of their line of development. Finally, an attempt will be made to analyse the factors which maintained the efficiency of these aircraft at a high level for a period of ten years.