What would you call a country that called for "a structure under which [Europe] can dwell in peace, in safety and in freedom ... a kind of United States of Europe" at the end of the Second World War (Winston Churchill, 1946), but refused to join that structure when its European neighbours actually began building it (European Economic Community, 1957)?
What would you call that country if it changed its mind and asked to join the EEC in 1961, a goal it finally achieved in 1973 under Conservative Prime Minister Edward Heath - only to demand a renegotiation of its terms of membership and hold an in/out referendum on EEC membership under a Labour government two years later?
What would you say if that country then demanded another renegotiation of the terms of membership under Conservative Prime Minister Margaret Thatcher in 1984, and insisted on opting out of the planned single currency when the countries of the European Community (as it now styled itself) signed the Treaty of Maastricht in 1992?
And what would you say about that country's behaviour if another Conservative Prime Minister, David Cameron, demanded another renegotiation on the terms of membership in what is now called the European Union in 2013, and promised another referendum once the results were known? The word "ambivalent" would certainly spring to mind. "Capricious" also has a strong claim. But the adjective that really sums up Britain's behaviour in its 70-year love-hate relationship with the European project is "petulant".
There's going to be another referendum on whether the United Kingdom should stay in the European Union on June 23. Not that Prime Minister Cameron wants to leave the EU, of course. His 2013 promise of a referendum was an attempt to steal votes from the United Kingdom Independence Party, which wanted to leave, in the 2015 election.