Why Britain built the Weapon-class destroyers

Why were the Weapon-class destroyers built, and what problem were they meant to solve?

They matched medium-sized yards that could not build Battle-class ships, preserving production capacity for a longer war.

Some British yards were too small for Battle-class destroyers but too capable to leave idle or assign only very small escorts. The Weapon class was sized to use those facilities and add hulls without competing for the largest building positions. Had the Pacific war continued into 1946 or 1947, the extra destroyers would have been operationally valuable. The design therefore makes most sense as an industrial mobilization solution rather than as an attempt to create the ideal destroyer in isolation.