What would the Royal Navy look like if the First World War never happened?
Short answerIt would build many more 15-inch battleships and probably move to heavier guns, while naval aviation matured much more slowly without wartime pressure.
NotesContinued competition with Germany would keep British capital-ship construction moving after the Queen Elizabeth and Revenge classes. Completing the full planned runs would give the Royal Navy roughly fourteen 15-inch battleships before another jump in caliber or triple-turret design. The fleet could then move toward 16-, 16.5-, or 18-inch weapons and become even more battleship-heavy. Aviation would develop on a slower peacetime curve because war no longer brings so many people into the technical problems or creates the Royal Air Force, leaving aircraft of roughly 1920 capability relevant much later.