In 1945 the Admiralty issued a requirement for a new anti-submarine/strike aircraft, to which Fairey responded., however it took ten years before the Gannet reached active service.
Faced with the problem of getting a heavy aircraft off a short carrier deck Fairey Aviation selected the Armstrong Siddeley Mamba turboprop and suggested coupling two of these engines together in tandem, driving a co-axial propellor. The result was the Double Mamba. Each half of the powerplant had seperate controls and the two independent power sections would be used together in the crucial take-off phase, allowing the pilot to shut one half down and feather the prop to extend the duration and range of the patrols. Additionally, the engine could refuel from its aircraft carriers' own diesel fuel bunker, eliminating special aviation gas tanks on board. The Gannet was fitted with arrester gear to allow recovery back to the deck of the carrier.
Additional verticle fins were added to the tailplane to counter stability problems associated with the aircraft’s radome encountered in testing. Ordinarily this could have been alleviated with a larger tail unit but this was unnacceptable due to cost and space constraints encountered onboard carriers.
The first Gannets were designated Gannet AS.1, the first operational squadron , No 826, formed up in January 1955. The 170th production AS.1 received a more powerful Double Mamba 101 engine and became the Gannet AS.4, this variant equipping the Royal Navy’s ASW squadrons until 1960, when it began to be replaced by Wessex ASW helicopters.
The Gannet served onboard HMS Illustrious, HMS Ark Royal and HMS Eagle. Eventually, 255 of the uprated version (Gannet AS Mk4) satisfied the Fleet Air Arms need to replace aging Fireflies and Avengers.
The Mks T2 and T4 were trainers. The last version of the Gannet was the AEW.3 early warning aircraft, which equipped four flights of No 849 Squadron. The first prototype was delivered in 1958. The Mk3 incorporated major re-designs including a new fuselage and longer undercarriage to allow for a radome.