The arithmetic behind King George V's 14-inch guns

Why did Britain choose 14-inch guns in 1936 when European powers were announcing 15-inch battleships?

Political leadership mattered, and a planned twelve-gun 14-inch battery promised a strong volume of fire; the logic became weaker when the ship ended up with ten guns.

Britain's choice of 14-inch weapons partly reflected a desire to demonstrate political leadership while European rivals announced 15-inch ships. The naval argument depended on fitting twelve 14-inch guns, whose greater number of shells could plausibly compete with eight 15-inch weapons. Once the design fell to ten 14-inch guns, that volume-of-fire advantage became much less convincing against eight or nine larger guns. The diplomatic case and the original armament arithmetic both shaped the decision.