Watch the Tories sidling up to the Lib Dems: the foundations for a post-election pact

Now that Francis Maude is no longer lurking around Conservative headquarters dampening any high spirits he might encounter, bubbles of optimism are allowed to float with impunity around Team Cameron. For the last three weeks, the Tories have enjoyed double-digit opinion poll leads. The consensus in Westminster is that the Conservatives (or, more accurately, Boris Johnson) will capture London next month. Some bookmakers are now predicting an outright Conservative victory at the general election, whenever Gordon Brown deigns to hold it. The end of opposition appears, at last, to be in sight.

In the absence of Mr Maude, the cure for Tory euphoria lies in the other dismal science: psephology. The British electoral system remains notoriously biased against the Conservatives, such that a ten-point lead over Labour is a necessity rather than a luxurious advantage for David Cameron. To achieve a Tory victory will require a 7 per cent swing — something that has only been achieved twice, in 1945 and 1997.