"When the French Prime Minister, Monsieur Mollet was recently in London he raised with the prime minister the possibility of a union between the United Kingdom and France."
...
So, when Eden turned down his request for a union between France and Britain the French prime minister came up with another proposal.
This time, while Eden was on a visit to Paris, he requested that France be allowed to join the British Commonwealth.
A secret document from 28 September 1956 records the surprisingly enthusiastic way the British premier responded to the proposal when he discussed it with his Cabinet Secretary, Sir Norman Brook.
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Stammering repeatedly he (a current professor of history) said: "Really I am stuttering because this idea is so preposterous. The idea of joining the Commonwealth and accepting the headship of Her Majesty would not have gone down well. If this had been suggested more recently Mollet might have found himself in court."
http://news.bbc.co.uk/1/hi/uk/6261885.stmThis was the year before the EU (OK, accurately, the predecessor to the EU) was founded.
I can't have seen either plan working. But it might have been amsuing to see the spluttering of nationalists on either side.