The Lion class were a class of four battleships for the British Royal Navy of which two were laid down and never completed. They were an elaboration of the King George V class and were intended to replace the World War I vintage Revenge class. The Revenge class had been built with economy in mind giving them a top speed of only 21 knots, and they were therefore not suitable candidates for reconstruction.
The appearance of the Lions closely followed that of the KGVs, but with a transom stern to improve steaming efficiency. Secondary armament would have been similar to the KGVs, with sixteen 5.25 inch guns in eight twin turrets, arranged in superfiring pairs on each side fore and aft of the athwartships aircraft catapult. The Lions would have been contemporaries of the US Navy's Iowa class, with both ships free of the treaty restrictions (the Treaty-conforming KGVs were contemporaries of the North Carolinas).
Serious thought was given to resuming construction of at least one Lion to a new design immediately following the Second World War. However these proposals all came to naught due to both the financial situation of postwar Britain and the realization that, if the ships were to be given adequate protection from air attacks, the amount of deck armour they would have to carry would be excessively heavy.
In the event only two battleships were completed after World War II, the British and the French Jean Bart. Jean Bart's construction had been interrupted by the fall of France in 1940, and Vanguard had been designed during the war to take advantage of four spare turrets removed from the two Glorious class large light cruisers during their conversion to aircraft carriers during the 1920s.