There were also other proposals for conversion. By early 1944 it was clear that the British Pacific Fleet would badly need new aircraft maintenance ships equivalent to HMS Unicorn, (see chapter 13 for the reasoning); the two candidates were an American supplied escort carrier and a Colossus. The escort carrier would be an equivalent to one-third of a Unicorn, the light fleet carrier to one-half. The new British Pacific Fleet would need up to three Unicorn equivalents by the end of 1945, that is, nine escort carrier hulls or six light fleet carrier hulls. By this time the first four ships (Colossus, Glory, Vengeance and Venerable) were too far along to convert, but the next four (Edgar, Mars, Warrior and Theseus) were viable candidates. Given an early enough decision, two ships (one unit) could be available at the end of 1944, followed by another in April 1945 and the third in the latter half of 1945. Another alternative, to build a new specialist ship, was rejected because it would have taken too long, even if shipyard capacity could be made available.
In the event, the light fleet carrier conversion was chosen. Ships selected well before completion could be altered internally, and time (up to two months) would actually be saved, because considerable electrical work and piping could be omitted, particularly if endurance was reduced to that required of a conventional fleet auxiliary (5,000nm at 12 knots). HMS Edgar and HMS Mars were chosen, and renamed Perseus and Pioneer respectively.