What changes if the Royal Navy keeps control of the Fleet Air Arm from 1918?
Short answerThe entire naval-aircraft procurement path changes, with the Royal Navy controlling its own requirements rather than merely deleting individual historical aircraft.
NotesThe counterfactual has to begin with the 1918 creation of the Royal Air Force rather than with aircraft already designed in the late 1930s. In that timeline, types such as the Blackburn Roc would not simply be cancelled because the procurement system that produced them would be different. The Royal Navy would control its own aircraft requirements and construction choices. The Admiralty's institutional power would also limit the Air Ministry's influence over those decisions.