How revealing Yamato in 1941 could have changed Allied planning

What might have happened if Japan publicly revealed Yamato and her eighteen-inch guns before Pearl Harbor?

The revelation could have altered Pacific deployments, accelerated Allied countermeasures, and generated political pressure for equally large guns or ships.

Politicians would likely react strongly to evidence that Japan possessed larger-gunned battleships than any Western fleet. The United States might reinforce Pearl Harbor or pull older battleships back, while naval planners looked for ways to slow Yamato with carrier strikes before committing their own heavy ships. In Britain, Nelson and Rodney would become obvious counters and pressure for a new super-battleship could revive. The military calculation that Japan had only two such ships would compete with the political impact of an opponent visibly possessing the biggest capital ship. A later anecdote about briefly considering whether Queen Elizabeth-class carriers could be lengthened after comparison with a Russian carrier shows how prestige can collide with dock size and conversion cost.