Both the big parties are groping their way towards an In/Out vote. (We can discount anything the LibDems say after this). But they are following different timetables. Labour inclines to a snap poll immediately after the general election, designed to split the Conservatives and confirm Britain's membership. Most Tories, as far as I can tell, want such a vote after a renegotiation. The idea seems to be to use the next treaty talks to strike a grand bargain: Britain will be helpful to those states wishing to establish a fiscal union among themselves if, in exchange, we can amicably derogate from the aspects of the EU which we dislike.