Would the Royal Navy strip submarines from western theaters to reinforce India and Australia?
Short answerIt would probably send more, especially from the Atlantic, though Britain already operated a significant submarine force from Australia.
NotesThe Royal Navy historically transferred submarines eastward, particularly from the Atlantic, while retaining more in the Mediterranean. A larger Japanese threat to Australia would likely demand additional redeployment. Those boats would reinforce an existing British submarine presence operating from Australia rather than create a force from nothing. The answer corrects a Pacific-war picture that often notices American submarine operations while overlooking the Royal Navy's contribution.