As opinion polls reveal that half the British population would vote in favour of withdrawal from the European Union, it seems the political class is catching up with public opinion when it comes to the EU.

While perhaps just dozens of MPs are publicly calling for a referendum on the UK's EU membership, behind closed doors there are many more closet secessionists: at least 40 per cent of Conservative MPs according to one party insider.

"In public I call for renegotiation of the Lisbon treaty. In private I argue for complete withdrawal from the European Union. And there are plenty of others like me," says one anonymous sceptic.

Edward Stourton asks whether the crisis in the eurozone has emboldened more politicians to speak frankly on their attitudes towards EU membership and talks to supporters of withdrawal from both the left and right wings of British politics.

Producer: Hannah Barnes.