A fast Queen Elizabeth-derived capital ship may have carried 18-inch guns. British planners knew other navies were working on 16-inch weapons, so a move to only 16.5 inches offered little advantage. The 18-inch guns later fitted to Furious show that a larger weapon was already being developed from the 15-inch family. Agincourt may have been a conventional Queen Elizabeth-class ship or something much more unusual, but the surviving evidence does not support a secure reconstruction. Once war clarified what Germany could build, cancelling an exceptional ship became easier to justify.
Notable Point · 18:20-20:34
Why an 18-inch British capital ship was plausible
Foreign work on 16-inch guns made an 18-inch British step more plausible than a small intermediate increase, though the exact Agincourt design remains uncertain.