The two ships built were heavily modified and diverged over their service lives.

However, it was realised that the hangar height would not be sufficient for the new aircraft that were expected to enter service, so the design was considerably enlarged.

[1] Four ships were laid down between 1942 and 1943 during World War II as part of the British naval buildup – Africa, Irresistible, Audacious and Eagle.

As the builds of Audacious (renamed Eagle) and Irresistible (renamed Ark Royal) progressed they differed so much that they effectively became the lead (and sole) ships of each of their own classes.

They formed the backbone of the postwar carrier fleet, and were much modified.