Boris Johnson could have quoted Dickens on his way to ask the Queen for the dissolution of Parliament this week: “It was the best of times; it was the worst of times …” It was the best because he was ahead in the polls and he had a deal with Brussels with which to confound his enemies, and Labour had not yet replaced Jeremy Corbyn with someone more electable; and the worst because absolutely nobody knows the outcome of the general election campaign that he has just launched. He could easily end up on the political scaffold, no doubt congratulating himself on a heroic sacrifice.

Not the least of the reasons for the uncertainty is the way political loyalties have collapsed under the pressure of Brexit. How someone voted in the 2016 referendum is thought to be as good or better a predictor as to how they will vote this time than how they voted in the 2017 general election, when the fault line of Labour versus Conservative reasserted itself.

It is not just the electorate that is split asunder by Brexit. It is also true of the two main parliamentary parties; and it is true of their leaderships. Since 2017 both parties have moved further towards the ends of the political spectrum.