A 4.5-inch standard weapon for the Royal Navy

Would the British 4.5-inch gun be a better fleet-wide choice than the 5.25- or 4.7-inch weapons?

Yes; its performance was adequate and standardization would greatly simplify supply across every theater.

A universal 4.5-inch mount could equip Didos, C- and D-class cruisers, battleship secondary batteries, and destroyers while offering useful high-angle performance. The calibre was newer than the 4.7-inch and better suited to high-elevation work, while remaining adequate against destroyers and smaller surface targets. Existing Flower-class corvettes could continue using surplus First World War four-inch guns rather than being rebuilt, while Black Swans and later Castles were more plausible 4.5-inch candidates. That distinction makes standardisation a forward procurement policy rather than a wasteful universal refit. Common ammunition would simplify supply in the Far East, Mediterranean, and North Atlantic. Many broadly effective weapons would produce a stronger fleet than a few individually optimal but incompatible systems.