Instead of feuding over farm spending and Iraq, the French and British might now be celebrating four decades of union under Queen Elizabeth II if London had accepted a French plan drafted at the height of the Suez crisis in 1956.

Guy Mollet, then the French Prime Minister, proposed a merger as a way of sealing their alliance against threats in the Middle East.

Sir Anthony Eden, the British Prime Minister, rejected the first idea but was keen to bring France into the Commonwealth, according to National Archive documents cited by a BBC Radio 4 documentary.

The 1956 plan was an attempt to revive a still-born Franco-British union that Winston Churchill proclaimed in June 1940. Britain stayed out of the 1955 Franco-German scheme to introduce the European Common Market, the future EU.

In September 1956 Britain and France were desperate to regain control of the Suez Canal, which had been nationalised by President Nasser. Mollet, a socialist and English teacher, wanted to shore up British support for military action. In November, along with Israel, the two nations staged their ill-fated invasion.

According to the 1956 Cabinet memorandum: “M Mollet . . . raised with the Prime Minister the possibility of a union between the United Kingdom and France.”

A Cabinet official recorded the enthusiastic way that Eden responded when he discussed it with Sir Norman Brook, the Cabinet Secretary: “Sir Norman Brook . . . informed me the PM told him he thought in the light of his talks with the French: that we should give consideration to France joining the Commonwealth; that M Mollet had not thought there need be difficulty over France accepting the headship of her Majesty; that the French would welcome a common citizenship arrangement on the Irish basis.”

The idea was dropped quietly after opposition from Whitehall. James Ellison, a London University historian, said that France was not the only candidate. “Belgium, the Netherlands and Norway were also discussed. The Treasury advised that the instability of European economies would not do the Commonwealth a lot of good.”

The Foreign Office also advised against a Franco-British union when Britain was trying to promote a more multilateral arrangement for Europe that included the Germans, said Mr Ellison.

Eden resigned when Britain and France were forced by the United States into a withdrawal from Suez. Mollet survived but within two years France’s Fourth Republic collapsed under the pressure of the Algerian war and General Charles de Gaulle was called in to become president under a new constitution.

French historians played down the seriousness of Mollet’s revival of the June 1940 Franco-British scheme for a temporary union between the wartime allies. That union was the brainchild of Jean Monnet who later became the architect of the Common Market.

Neither Mollet nor Eden had left any records on the 1956 scheme, Denis Lefèbvre, a biographer of Mollet, said yesterday. “It is not certain that these men thought that the scheme was workable,” he said. “There was no follow-through. The proposal was not proof of Mollet’s submission but rather a way of binding in Eden and putting pressure on him.”

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