One interpretation is that Henderson expected to have until around 1942 and intended to replace the 4.7-inch gun when a suitable mounting was ready. A bulk 4.5-inch order in 1936 or 1937 is raised as an alternative that was never pursued. Political constraints also accompanied the need to get destroyers into service and improve their close-range air defence with weapons such as the pom-pom. High-angle fire imposed loads that called for reinforcement in the mounting and supporting hull structure, adding weight to the installation.
Notable Point · 33:08-34:59
Henderson and the expected time for rearmament
A lighter 4.5-inch mount took time to develop, and prewar planning may have assumed time the Navy did not have.