A modified version of the U.S. Navy's F4F, the Grumman Model G-36A provided the Royal Navy with its first high-performance single-seat monoplane carrier fighter. Named "Martlet I" in British service, these 81 aircraft had originally been ordered by France and were taken over by the British after France surrendered. Powered by 1,240 horsepower Wright "Cyclone" radial engines, the first "Martlets" entered service in September 1940, and achieved the first "kill" for any American-built fighter in British service on Christmas day of that year, when a German Ju-88 was forced down near Scapa Flow.

Several other versions of the design followed in 1941. The 100 "Martlet II" and 30 "Martlet III" types had 1,200 horsepower Pratt & Whitney "Twin Wasp" engines, like the American F4Fs. Most "Martlet IIs" also had folding wings. These early "Martlets" had considerable combat service, flying from shore bases and from aircraft carriers, including the pioneer escort carrier, HMS Audacity. Very maneuverable by European standards, and heavily armed, they were a serious threat to enemy aircraft.

The "Cyclone" powered Grumman F4F-4B, a type built solely for transfer to the British, became the "Martlet IV". Like later versions of the design, these 220 planes were provided through Lend-Lease, rather than by sale, and were delivered starting in 1942. Next in the series were over 300 "Martlet Vs", identical to the U.S. Navy's General Motors-built FM-1, with Pratt & Whitney engines. Surviving units of these two types were redesignated "Wildcat IV" and "Wildcat V" in January 1944. There were also 340 "Wildcat VI" fighters, the equivalent to the USN's FM-2. The first of these arrived in 1944.

The later British "Martlets" and "Wildcats" were extensively used at sea, primarily based on escort carriers though some were also carried aboard fleet carriers. In addition to anti-submarine work, teamed with "Swordfish" strike aircraft, they participated in amphibious operations in the Mediterranean and Normandy, helped make oceanic aerial reconnaissance unhealthy for the German air force and successfully competed with enemy fighters for control of the air over European shores.