The best hope for Rishi Sunak when he started his campaign was a repeat of Tory fortunes as in previous elections such as 1992 and 2015: a return to the Tory fold of previous party voters who had become won't-vote or don't-know voters rather than being attracted to a lukewarm Labour appeal. If that were to happen, the Conservatives might still lose seats but at worst end up as a substantial Opposition in the House of Commons. This hasn't happened.
Instead, Tory support has worsened to the point that the party now faces its worst defeat in its history, taking only 60 seats in the latest Electoral Calculus prediction. More than that, it faces the prospect of losing its position as the Official Opposition by falling behind the Liberal Democrats in the number of MPs it has in the House of Commons.
Blue wall at risk: The village of Lacock in the seat of Chippenham is predicted to swing from Conservative to Liberal Democrat.
The simple explanation for this failure is that Sunak's hopes were based on history repeating itself rather than on a theory explaining why former Tories were not going to return to the ranks. First of all, the record of John Major's government in 1992 did not have the massive quantity of mistakes of the party that Sunak now leads. Secondly, a major grievance in 2015 was the existence of a coalition government. Voting Tory got rid of that problem. Thirdly, the 2019 majority of the Tories was put together with an appeal that cut across party line: Get Brexit done, and Brexit is now done.
The Conservative record of infighting in the past five years is far worse than any previous situation. Boris Johnson disappeared due to breaking rules, Liz Truss wilted rapidly when she tried to apply free-market theories and Sunak has had to preside over a cumulative rise in prices unprecedented in the lifetime of most voters. Moreover, he has made acting on immigration a key issue but has failed to produce results.
Concurrently, Labour is no longer led by Jeremy Corbyn and the Liberals are not propounding incredible policies but a simple vote-winning appeal: vote Lib Dem to turn the Tories out. The only party defending a bigger record of failure, corruption and incompetence is the Scottish National Party.
Add to this the fact that Sunak's centrism has encouraged Nigel Farage to return to electoral politics, giving disaffected Tories the alternative of voting for the harder-right Reform Party. It offers the option of voting for what you would like to happen. The fact that Reform would not form a government is unimportant compared to the fact a Reform vote will push the Tories further to the right in the next Parliament.
Sunak's performance has also blown a hole in theories of the prime minister's power. The power to call an election has turned out to be the means of shortening his life in Downing Street by picking a date for his execution rather than letting election law prolong his time in office. Unwittingly, Sunak has underscored an often neglected character of a charismatic leader: the capacity to destroy institutions, in his case, the centuries-old Tory party. He leaves to an MP in the new House of Commons the greater challenge of creating a new institution in place of the one that has been destroyed. On present form Sunak will not face that challenge but Nigel Farage will.
Prof Richard Rose is Britain's senior election expert, having written about 18 elections since 1959.