There have been reports that Cameron has been threatening to bring forward the date of his planned In/Out EU referendum if Jean Claude Juncker gets the job of President of the EU Commission. Ladbrokes have pulled the market on Juncker’s chances, as that now looks like a certainty.
If anyone thinks these reports are true and this is any more than a bluff, you can back a 2015 or 2016 referendum at nice prices.
Of course, the biggest obstacle to a referendum happening is that the Tories need to still be in government after the next election.