The British veto

There was an exquisite moment captured on camera during those all-night talks at last week's EU summit in Brussels -- when the French President Nicolas Sarkozy and British Prime Minister David Cameron came face to face. David Cameron, with his posh semi aristocratic background, reaches out a hand - and Sarkozy totally blanks him - not a smile, not a wink, not a nod - nothing. You needn't be a body language expert to deconstruct that one.

The French President was seething after the British had deployed their nuclear weapon, commonly known as the veto. And only a French diplomat could have come up with this metaphor: he said that Mr Cameron's attempt to dictate terms for a currency of which he was not a member was like a man coming to a wife-swapping party ... without his wife.

Relations between Britain and the rest of the European Union have always been difficult - and there have been some famous stand offs. Margaret Thatcher drove her then European partners mad with her attempts to cut Britain's financial contributions. Some years later, her successor John Major some years later withdrew cooperation from the EU institutions after a row over sovereignty. But no British Prime Minister has ever used the veto. Until now.

What happened last week in Brussels represents a fundamental change in British foreign policy - and arguably - and incredibly - sets Britain on a one way course to a door marked 'exit'. The view here has always been that you work on the inside to shape and influence events. You wheel and deal, make compromises where necessary - but always stay at the table. Now the 26 other members of the EU will form their own Euro plus group to deal with the debt crisis and to try to stabilise their currency. They will meet monthly - and Britain won't be there.

The one thing that has united every British Prime Minister since we joined in 1973 is the belief that our national interest is best served by being part of Europe. And David Cameron still believes that. But Britain could now find itself in a position where key future decisions will be beyond our control. Those politicians who've long been demanding a referendum on whether Britain should leave the EU altogether believe last week's seismic events have brought that vote a massive step closer. This is Jon Sopel for CBS News in London.