The London treaty might answer the speed gap with scheduled capital-ship construction

The counterfactual reaches a fork at the first London treaty: if rival navies are unconcerned by British speed, nothing need change. If they demand new ships to close the gap, construction would require either a negotiated allowance or the breakdown of the treaty system. One proposed bargain would permit Britain and the United States roughly five new capital ships each, Japan three, and France and Italy two each over a six-to-seven-year cycle. That timing reflects the tension between convenient building periods, twenty-year replacement, and the tonnage limits. Britain might continue with 15-inch guns because the saved armament weight bought speed and other capabilities. Construction beginning around 1930 would initially favor F3 derivatives and other contemporary designs, with later development increasingly difficult to predict. The possibility that controlled replacement could prolong arms limitation remains conditional on the powers accepting the bargain.