Turn the dial on your the time machine to May 2015. It's a spring morning and David Cameron, against all the odds, is walking up Downing Street. He's just been to Buckingham Palace, where the Queen has handed over the keys to the sole tenancy of Downing Street.
You've probably watched the telly for a few hours and seen dozens of Eurosceptic Tory MPs wandering into the TV studios, bragging about their election manifestos, written in their own blood. In the face of Cameron's 2010 'stop obsessing about Europe', they had been rabbiting on about it for five years. Many have promised their electorate they would vote to exit the EU no matter what was on offer.
In 2014 ninety five of them signed a letter to him with terms that would mean a pretty sharpish exit from the EU. That's nearly one-third of the Tory parliamentary party. So in the 2015 General Election no one is surprised to see those ninety-five substantially increased. These MPs will have no interest in any re-negotiations Cameron promised, They want out. They see Cameron returning from Brussels with any deal like Neville Chamberlain returning from Munich in 1938 with his note signed by Herr Hitler.
Yet Cameron will be asking the country for a YES vote. Over one third of his parliamentary party and most of the media against him equals some hope!
If he were to lose the vote, it's hard to see how he could survive.
And now I turn the big dial on the time machine back to May 1846. Sir Robert Peel has managed to pass a Bill to repeal the Corn Laws. The result? Peel resigns, his party splits and the Tories are out of power for over 30 years.