Swapping Royal Navy and US Navy high commands

What if the Royal Navy and US Navy high commands exchanged places one week before Pearl Harbor?

British wartime experience could improve American readiness, but both commands would have to learn unfamiliar fleets and institutions while the wider outcome remained an Allied victory.

British officers would arrive in the United States after two years of war, while the Americans would enter British commands already conducting wartime operations. That difference could make British officers more inclined to pass on a warning about a possible attack on Pearl Harbor and order full readiness. Both groups would lose their familiarity with their own ships, chains of command, and organizational habits. The British would have a week to learn their new commands before the attack, whereas the Americans would need help from experienced British subordinates immediately. A cautious British approach is proposed as useful against Japanese surprises, while American preferences for concentrated carrier strikes are questioned in the Mediterranean. The scope of the swap remains an assumption, with admirals and senior staffs exchanged while captains and more junior officers stay. British officers are also imagined ordering night exercises despite fuel-budget constraints and then seeking the funds to sustain them. The ultimate outcome is still judged to be an Allied victory, with the larger differences appearing in readiness and early operations.