The Conservative contest for party leadership between Liz Truss and Rishi Sunak is the start of a continuing process of change in who governs Britain. Polls of Tory party members indicate that next week Liz Truss will become the fourth Conservative prime minister in twelve years. This month's polls of the electorate as a whole forecast that in two years Sir Keir Starmer will enter Downing Street as the first Labour leader to win a general election since Tony Blair.
The slight rise in Labour's popular support involves far more voters than are participating in the ballot of Conservative Party members to decide the next prime minister. It is also far more important politically. The slanging match between Truss and Sunak is tipping the likely outcome of the next general election from a hung parliament in which Labour lacks an absolute majority to an outcome in which it wins enough MPs to be in secure control of government for the five-year life of the next Parliament.
The central prediction of Electoral Calculus analysis is that Labour can win at least a hundred more seats than the Conservatives. On present showing, there is even a one in five chance that Labour could top Labour's record win of 418 seats in 1997. As long as Labour is the largest party in the House of Commons, and there is a 88 percent probability on current figures, Keir Starmer is in position to take the key to Downing Street from Liz Truss in two years time.
Boris Johnson leaves the new Prime Minister a Janus-faced legacy. Looking backwards, Liz Truss inherits a comfortable parliamentary majority based on 365 Conservative seats won at the 2019 general election. However, looking forward toward the next election the Conservatives face a predicted loss of 143 seats if a ballot were held now. Moreover, there is a 30pc chance of doing worse than in 1997, when a tired Tory government won only 165 seats, thereby suffering its worst electoral defeat in modern political history.
The various groups that collectively constitute Britain's third electoral force can expect to gain seats. The central prediction is that the Liberal Democrats would gain eight MPs, the Scottish nationalists three MPs and Plaid Cymru, one. If the Tory vote collapsed in its Blue Wall seats in the South of England, the Liberal Democrats might gain two dozen more seats. However, as long as Labour had an absolute majority, all these parties would be bereft of political influence at Westminster. They would be on the Opposition benches along with Conservative MPs, vainly voting against a Labour government with a secure majority.
Richard Rose is Britain's senior psephologist and an expert on party government. His new book 'How Sick is British Democracy?: a Clinical Analysis' is published by Palgrave.