How an F3-derived fast battleship could preserve 15-inch production

The proposal replaces the Nelson-class route with a fast battleship derived from the F3 design and armed with 15-inch/50 guns. Continuing the established shell family avoids the problems associated with the new British 16-inch ammunition and keeps a modern 15-inch production line alive. That line could support later upgrades and offer a ready nine-gun alternative if the planned 14-inch fit for the next generation became unsatisfactory. The Royal Navy would also enter the Second World War with two additional fast capital ships to share operational demands. The counterfactual therefore links one design choice to ammunition standardization, industrial continuity, and later fleet composition.