How Britain and America might answer early Yamato plans

How would the major Allied navies respond if they received complete Yamato plans early enough to build against them?

America would accelerate the Montanas, while Britain would speed the Lions and choose between revived 18-inch work and a heavier-volume 16-inch battery.

The United States would probably prioritize Montana-class construction ahead of more Iowas. Britain would accelerate the Lions and reopen its earlier 18-inch gun work if it judged a direct calibre match necessary. Both navies might instead favor twelve 16-inch guns because their higher rate of fire could put more shells on target for only a modest sacrifice in range. France and Canada lacked the industrial base for a comparable response, making the counterfactual primarily an Anglo-American procurement race.