“The thunder had long grumbled in the air; and yet when the bolt fell, most of our party appeared as much surprised as if they had had no reason to expect it.” That rueful recollection by Tory leader Lord Bolingbroke of his party’s unpreparedness for the catastrophe of the Whig coup of 1714 and the general election of 1715, which put the Tories out of office for 69 years, has an eerie resonance of the predicament of the Conservative Party today.

History does not repeat itself – the constant permutations of events and personalities over the centuries make such a pattern impossible – but it does sometimes move in ellipses. That is especially the case in situations where the institutional context has remained broadly similar, as in the instance of a British parliamentary general election, when the size of the electorate has radically increased, but otherwise the party system and rules of engagement are little changed, compared with the dramatic revolutions in constitutional arrangements in other countries over the same period.