After the failure of the London Naval Treaty of 1936, the British Admiralty returned to designing heavy cruisers. In January 1938, the lead engineer of the Naval Shipbuilding Office suggested a number of projects for a heavy cruiser with a displacement of 20,000 tons and armament represented by 203–234 mm caliber guns. One of the arrangements included three quadruple-gun turrets. A similar armament option was revisited in September 1939 while preparing preliminary designs for the A-class cruiser.