The choice of gun and the mix of quadruple and twin turrets for the main battery of the King George Vs had been dictated by the Second London Naval Treaty, which limited battleships to standard displacement and a main calibre of 14 inches. However, when the Japanese Government refused to agree to its terms, the maximum calibre allowed reverted to 16 inches in April 1937. The Board of Admiralty then began preliminary design work on a 35,000-ton ship armed with 16-inch guns and they were promising enough that the Director of Naval Construction (DNC) was ordered to further investigate such designs, providing for several aircraft as well. To save design time, many of the features of the King George Vs were incorporated in the new design, but the limited size of the ship was a real challenge fo