In 1956, the British and French prime ministers, Sir Anthony Eden and Guy Mollet, discussed the possibility of France joining the Commonwealth. The proposal was never accepted and the following year France signed the Treaty of Rome, which established the European Economic Community, the precursor to the European Union. In November 1956, Britain and France invaded Egypt in an ultimately unsuccessful attempt to capture the Suez Canal. Lord Mountbatten claimed the Queen was opposed to the invasion, though Eden denied it. Eden resigned two months later.

When did the prime ministers of Britain and France discuss the idea of France joining the Commonwealth?