In the twenty-one elections since 1945, the winning party has only twice gained as many as 400 MPs. Labour did this in 1997 and again in 2001 under Tony Blair's leadership. If Labour's current lead over the Conservatives holds until next year's general election, Labour would again be in the 400 club, winning 475 seats.
Of course, polls can overestimate or underestimate the size of the front-runner's lead and the first-past-the-post electoral system can play some odd tricks when converting votes into seats. Allowing for margins of error shows that Labour is not certain to remain in the 400 club. Electoral Calculus reckons that there is a greater probability of Labour winning more than 500 MPs than seeing its ranks fall between 399 and 338 MPs.
For Sir Keir Starmer the size of Labour's majority is less important than that it is big enough to hold for the five-year life of the next Parliament. The current figures show a 96 percent probability that Labour would have an absolute majority in the House of Commons. This is a reminder that an Opposition leader does not need to project a clear vision to win an election.
Labour's lead is due to voters having a clear vision of the Conservative government: it isn't working. Tories agree. They have tried and ditched four prime ministers in the past seven years. Brexit's champions complain that the Conservative leadership has failed to make a success of leaving he European Union and the public investigation of the government's handling of the Covid crisis is showing that the Conservative government was unprepared to minimize the losses the pandemic created in money and lives. On current showing, it is predicted to win only a hundred seats.
The apt comparison between Rishi Sunak's position and that of John Major is the 1997 election, not the 1992 contest, when the Conservatives won a fourth consecutive term in government, notwithstanding having been down in the polls after ejecting Margaret Thatcher as leader. Eighteen months before the 1997 election the Conservative standing in the polls was as low as it is today notwithstanding the economy growing significantly. By the time the general election came, the Conservatives had regained some support but not enough to keep their hold of government. It won only 165 seats, less than half the number it had in the previous Parliament.
The Conservatives have eighteen months to recover ground, but the distance they must travel is great if they are to retain control of government. If they were to double the one hundred MPs that they are likely to gain on the basis of current polls, the Tories would be doing better than John Major did when the party went down to defeat. The Conservatives are not 100 percent certain to lose next year's election, but on today's showing there is only a one percent probability of the party coming first.
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.