Oerlikons for anti-aircraft protection. Calculations for a preliminary sketch design were completed in October and revealed a , ship at standard load and at deep load. More detailed studies were conducted in January 1945 and showed that the ship would actually displace at standard load and deep. This design was too large, so multiple variants were considered over the next several months, examining the effects of reducing side armour, underwater protection and the number of main and secondary gun turrets. The provisional staff requirements were issued in March and increased the speed to and set the endurance equal to that of the original design, which was slightly modified in April as 'Design B'. This greatly hampered the ability of the designers to reduce the size of the design as only those variants with two main gun turrets were below at standard displacement. The most radical variant, christened 'Design X', had an armour arrangement similar to the modernised battlecruiser with a pair of 16-inch and eight 4.5-inch turrets and had only minimal underwater protection, relying on tight compartmentalisation and strengthened internal bulkheads to localise damage. This yielded a ship at standard load. That same month a committee headed by Rear-Admiral Reginald Servaes reviewed all the proposals and the Admiralty requested a sketch design of 'X' with two 16-inch turrets, both forward of the superstructure as in the French , and a thicker waterline belt in May that the DNC designated 'X3'. This displaced at standard load. The following month the Admiralty asked that the 16-inch turrets be replaced by quadruple turrets and the DNC replied that no design work had been done on such turrets and would thus delay construction by 15 to 18 months and add about to the ship's displacement. The DNC asked permission to investigate further methods of reducing the size of 'B3' in July and work continued on both designs through October. By this time the impossibility of even maintaining the existing battle fleet, much less building such large battleships, had become clear in light of Britain's economic difficulties and further design work was informally suspended on all but the new Mk IV gun and its Mk III turret; this was finally cancelled by the First Sea Lord on 10 March 1949. Hybrid aircraft carrier On 8 January 1941, Rear-Admiral Bruce Fraser, Third Sea Lord and Controller of the Navy, asked the DNC to work up a