The 5.25"/50 gun was a large caliber DP (dual-purpose) gun that saw service in World War 2, and into the early Cold War. It was used on the King George V class battleships, Dido class cruisers and on the Vanguard battleship. (Vanguard was not completed until post-war) The mount for these guns is somewhat infamous for its unique appearance and shape, but was plagued with an ackward internal layout.