What was the Royal Navy's CVA-01 project?

What was CVA-01?

It was the Royal Navy's planned large catapult carrier intended to succeed Eagle and Ark Royal, but it was cancelled in the 1960s as Britain moved away from those carriers.

CVA-01 was the Royal Navy's planned catapult-and-arrestor carrier intended to enter service after Eagle and Ark Royal retired. The project was cancelled in the 1960s, and the existing large carriers were also marked for withdrawal. That decision is the historical break behind the stream's alternate-fleet questions. This short answer gives the essential baseline before the later discussion of Type 82 escorts, Hawkeyes, Hornets, and successor carriers.