Europe: has Cameron played a blinder by accident?

The general consensus reaction to the EU treaty negotiations last night is that they were a disaster for Dave Cameron and for Britain. Having vetoed changes to the Lisbon Treaty which would have started to move the Eurozone toward fiscal union, Cameron was then sidelined as the Eurozone states - plus 6 other countries - opened negotiations for a new deal outside the treaty framework which would create a "two-tier" EU with the UK on the outside track. According to the FT,

Several diplomats said Mr Cameron emerged from Friday morning’s negotiations deeply wounded, angering fellow EU leaders and getting no trade-offs for British interests.

But was it really a disaster for Cameron? Or could it in fact be the start of his biggest triumph? It seems to me that - although he didn't go into the negotiations wanting this outcome, and Europe has been a constant headache for him this year - Cameron may have accidentally come out of this summit in a strong position. With Britain isolated at the negotiating table, Dave now has the viable option of calling a referendum on Britain's membership of the EU - which he could well (if current opinion polling is any guide) win. We know that the majority of grassroots Tories, and many of the MPs, want to leave the EU. This would be Cameron's opportunity to shore up his position and delight the right of the party, who have been in the ascendancy since the 1980s at least.

The Lib Dems would probably leave the coalition if Cameron decided to go for a referendum on Europe (although who knows? They've swallowed much more bullshit than that without complaining in the last 18 months) but if so, Cameron would be tempted to call a general election on the EU issue. As far as I know the fixed term parliament bill is not on the statute book yet so he remains free to ask for a dissolution should he so wish... CORRECTION: Chris Brooke points out in the comments that it IS on the statute book so he can't ask for a dissolution immediately (but see comment thread below). Maybe 2012 will turn out to be an election year? Stranger things have happened.