Why the 4.5-inch gun won the postwar lineage

Why did the 5.25-inch gun not develop into a postwar family like the 4.5-inch weapon?

The Daring-class twin 4.5-inch mount was available, successful, and reusable across ships, while no equivalent 5.25-inch installation filled that role.

Gun development depended on a ship programme that kept the weapon in production and service. Battle-class destroyers carried the 4.5-inch gun, and the Daring class then provided a successful twin mounting adaptable to later ships. A comparable compact twin 5.25-inch system might have changed the choice, but it did not exist when the fleet needed one. Availability and platform integration can matter more than calibre in determining which weapon family survives.