general election delivers a big Labour majority. The Conservatives are reduced to a rump of 150 seats; the Liberal Democrats advance strongly in the Home Counties and end up with 40 to 50 seats. The strategy of being an anti-Tory protest party has worked well enough to turn the “Blue Wall” yellow.

But play their cards right and the Lib Dems could become the natural political home for the liberal centre right. Do that and British politics (or, to be more precise, English politics) could become a genuine three-party fight consisting of a social democratic Labour Party, a pro-market liberal party and a populist party of the right. In those circumstances, the populist Tories – dependent on an ageing cohort of voters – would have little chance of ever again forming a parliamentary majority.