The 45-calibre gun already served across numerous destroyer classes, sloops, submarines, and depot ships, giving a common programme a large installed base. The scenario extends to ships that historically received four-inch or 4.5-inch weapons, including C- and D-class anti-aircraft cruiser conversions and later new construction. This would preserve more surface capability in converted cruisers while eliminating the L-class 50-calibre branch. The forecast stops near the beginning of 1941 because every further ship-design choice compounds the uncertainty.
Chapter · 25:49-33:16
A single calibre reshapes much more than destroyers
Making 4.7 inch the common dual-purpose calibre would affect destroyers, sloops, cruiser conversions, and new ships historically armed with four-inch or 4.5-inch guns.