The Fairey Fulmar emerged in 1938 as an adaption to Specification O.8/38 for a two-seat Naval fighter, of the PA/34 day bomber. Differences included a small reduction in wing span, folding wings, deck-arrester gear, catapult points, modified cockpit canopy, Naval equipment and use of a 1,275 hp Merlin VIII. Armament comprised eight Browning 0.303-in (7.7-mm) guns in the wings and provision for a similar Vickers K gun in the rear cockpit. One P.4/34 prototype was converted to test features of Fairey Fulmar in March 1938.
   Fairey Fulmar I: Total of 250 built for FAA, first flight being on January 4, 1940, with Merlin VIII engine. Entered service June 1940 with No 808 Sqn, and first operations Sept/Oct 1940 on Malta convoys. Equipped 14 front-line squadrons by end-1942 including one in Egypt and one in India; also operated as night-intruder from shore bases, including Malta, and as night-fighter with No 813 Sqn ori Russian convoys. One captured and operated by Vichy French forces at Dakar in 1941.
   Fairey Fulmar II: As Fairey Fulmar I but fitted with 1,300 hp Merlin 30, Rotol propeller and tropical filters. One Mk I converted, first flown January 20, 1941, and 350 production aircraft delivered, ending February 1943.
   Squadrons: 700, 726, 731, 733, 739, 740, 746, 748, 756, 757, 759-762, 766-769, 772, 775, 778-782, 784, 787, 787Z, 788, 789, 790, 792-795, 798, 800, 803-809, 815, 822, 827, 835, 879, 881, 884, 886, 887, 889, 893, 897.