Ségolène Royal, the French Socialist presidential candidate, has been forced to clarify what she meant after appearing to call for Quebec’s “freedom”. Understandably taken aback, the Prime Minister of Canada, Stephen Harper, has reminded her that it is “highly inappropriate for a foreign leader to interfere in the democratic affairs of another country”.

Many French commentators are interpreting her gaffe as a sign of her unsuitability for the presidency. Yet, at least she supported Québecois separatism in a slip of the tongue. When Charles de Gaulle was President in 1967, he marked the 100th anniversary of Canada’s confederation by travelling to Quebec on a French warship. On arrival, he greeted the crowds with an unambiguous shout of “Vive le Québec libre!” Even less felicitous was his attempt to compare the scene with the 1944 liberation of Paris from the Nazis.

Infuriated, the Canadian Cabinet went into all-day session. De Gaulle responded by cancelling the next leg of his state visit. He caught the first available flight back to Orly airport.

Fortunately, the President kept his thoughts about the integrity of Royaume-Uni to himself. But both the Macmillan and Heath Governments had to decide how to respond to American interest in Anglo-Irish affairs.

President John F. Kennedy arrived in the Republic of Ireland in 1963. Laying claim to his Irish heritage, he received a pop-star welcome and joined in the singing of The Boys of Wexford, which celebrated the 1798 rising against the British, before laying a wreath on the graves of the 1916 Easter Rebellion’s leaders.

He also delivered a remarkable speech to the Irish Parliament. While avoiding mention of Ulster, he repeatedly referred to the country he was in as “free Ireland”. This fitted his theme that small countries could stand up to totalitarian ones, but given that southern Ireland had been “free” for more than 40 years, some wondered if he was also casting aspersions at Ulster.

Wisely, the Macmillan Government interpreted the speech in its literal — anti-communist — sense. However, eight years later, Edward Heath, then Prime Minister, described as “ignorant” a speech by JFK’s brother, Senator Edward Kennedy. Arguing against the nostrum that “America ought not to intervene in the affairs of another nation”, he called for a US Senate motion demanding Northern Ireland’s abolition. He insisted that Ulster’s existence was sustained only by “bayonets and bullets” against “oppressed minorities everywhere — yearning for liberty and the right of self-determination”.

Senator Kennedy’s failure to secure the Democratic presidential nomination prevented a serious breakdown between London and Washington. But it is not too late for him to demand Corsica’s freedom from France.