Did the Royal Navy design major ships around the limits of the Panama Canal?
Short answerNo; Suez was the important canal because British Far East reinforcement plans ran from the Mediterranean through the Indian Ocean.
NotesBritish designers did not treat Panama Canal dimensions as the controlling limit for ships such as HMS Ascendant. Wartime access through an American-controlled canal could not be assumed, and Panama did not match the navy's normal reinforcement geography. The Mediterranean Fleet was expected to act as the rapid-response force for the Indian Ocean, Singapore, and the South China Sea, with the Home Fleet following. Suez and the chain of British fueling stations mattered far more to design and deployment planning.