Wartime scarcity forced a quick compromise: Dido hulls were under construction, 5.25-inch guns were scarce, and 4.5-inch upper-deck mounts were available. The 4.5-inch system had been intended to supply high- and low-angle fire and might have armed Tribal-class destroyers had its development gone differently. The alternative five-inch programme had failed, while adapting the 4.7-inch weapon was judged difficult because of ammunition weight. Fixed 4.5-inch ammunition combined projectile and propellant in one round, promising a faster loading cycle and better high-angle fire than a heavier separate-loading arrangement.
Chapter · 10:03-12:14
An emergency answer to the 5.25-inch shortage
A shortage of 5.25-inch weapons turned available 4.5-inch dual-purpose mounts into a rapid wartime solution for unfinished Didos.