The Audacious-class aircraft carriers were a class of aircraft carriers proposed by the British government in the 1930s - 1940s and completed after the Second World War. The two ships built were heavily modified and diverged over their service lives. They were in operation from 1951 until 1979.
The Audacious class was originally designed as an expansion of the Implacable class with double storied hangars. 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.
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. At the end of hostilities Africa and Eagle were cancelled. Work on the remaining two was suspended. They would be renamed and built to differing designs in the 1950s.
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.