National opinion polls remind us that two by-election results are not good guides to general election results in 650 parliamentary constituencies. In by-elections the Conservatives lost Wakefield on a swing of 12.7 percent to Labour and lost Tiverton and Honiton to the Liberal Democrats on a swing of 29.9%. However, the swing in June's nationwide polls is just over 8 per cent to Labour.
The good news for Conservative MPs is that instead of most losing their seats on swings at by-election levels, two-thirds of Tory MPs would be re-elected if a general election vote reproduced the latest poll figures.
The bad news for Boris Johnson is that he would be turfed out of Downing Street, and on current poll figures he would also lose his Uxbridge and South Ruislip constituency. Senior Cabinet ministers such as Liz Truss, Priti Patel and Rishi Sunak would hold their seats, thereby being in a position to become the Conservative leader. However, spending five years leading a party in opposition is not the same as being a Cabinet minister within striking distance of becoming prime minister. On current poll figures there is only a 12 percent chance of the Conservatives gaining a majority.
For Sir Keir Starmer, the current situation is encouraging. Labour's nationwide support is up six percent from the 2019 general election, less than its gain at the Wakefield by-election that it won. This gives it a 72 percent probability of winning the most seats at the next general election, making Starmer prime minister. However, it isn't enough to encourage the Labour leader to feel secure in Downing Street.
At its current level of support, Labour would be twenty seats short of an absolute majority in Parliament. There is a 26 percent probability that it would be the largest party in the Commons but lack an absolute majority. Since Opposition seats are divided among ten different parties, it would take a coalition of at least five Opposition parties to carry a vote of no confidence against a Labour government so close to an absolute majority. However, in an increasingly fractious House of Commons a Labour government would be vulnerable to defeats on major issues of policy. There is a 46 percent chance that Labour could avoid this problem by winning an absolute majority in the Commons.
National support for the Liberal Democrats is barely changed, which would be likely to give it only six more MPs. If tactical voting gave the Liberal Democrats an additional dozen seats it would also give Labour enough extra seats to give Labour an absolute majority, thus dispensing with any need to negotiate with the Liberal Democrats for support.
A big Conservative defeat would add a few seats to the Scottish National Party's virtual monopoly of Scotland's parliamentary representation at Westminster. However, this would not give the SNP what it wants: a British government to agree to its demand for another independence referendum. For Labour to be dependent on the SNP for its hold on government, it would have to be heading a minority government with well under 300 MPs. On current poll showings there is less than a one in four chance that this would happen.
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.