All previous Seafires had single stage engines, fine for low altitude work and the defence of the fleet from all but high altitude bombers, which would have found moving warships an impossible target anyway. These Seafires were also well suited to supporting seaborne landings with low altitude bombing and strafing runs. However now it was time to take the war to the Japanese home islands and to fight a battle for air supremacy over those islands. In many ways the Battle of Britain in reverse. Now there was a need to get a really high performance, high altitude fighter to the British task forces. The Seafire 45 was the Spitfire 21 in naval guise with the two-stage Griffon engine. The new type 21 wing was kept and did not fold, and the type 45 had the normal bulged canopy. Armament was four cannon. Production 50.