The “turret fighter” concept dates back to the early thirties, and contrary to some histories, the first Turret Fighter used by the Royal Air Force was actually the Hawker Turret Demon biplane, which was tested and operated by No. 23 Squadron from 1934. A hydraulically operated power turret was fitted to a standard Demon fighter, itself a development of the Hawker Hart light bomber, and a considerable number was produced by Hawker and Boulton Paul. The turret itself was a Frazer-Nash creation, and all of the Boulton-Paul produced Demons had them, and some were retrofitted to the Hawker produced models. By 1938, the Turret Demon was being operated by No. 23 and No.64 Squadrons, but the type was out of first line service by 1939, being replaced by Blenheim Mk. 1F’s.