The 5.25-inch gun offered greater anti-surface power, especially valuable to a cruiser, but its twin mount was much heavier. Replacing the King George V class's eight twin mounts with 4.5-inch installations could save roughly 320 tons as well as space. Because the battleships already carried 14-inch guns, the need for an intermediate weapon against light cruisers was less compelling than it would be beside a much larger main battery. That creates a strong case for 4.5-inch battleship secondaries while leaving open whether the Dido-class cruisers would retain the larger weapon.
Chapter · 24:26-28:37
Could 4.5-inch guns replace the 5.25-inch battery?
Large-scale 4.5-inch production creates a serious weight and logistics case for using it on battleships, though cruisers still benefit from the 5.25-inch gun's punch.