I’ve mentioned before how Sinn Fein’s decision to abstain from participation in the House of Commons reduces the number of MPs needed for an absolute majority in parliament. Sinn Fein currently has five MPs. Because they do not take their seats, the total number of working members of the Commons is 645, not 650. And this means the number needed for an absolute majority in the Commons is 323, not 326.
But there are some other people we need to add to this calculation.
There’s the speaker, John Bercow, who though elected as a Conservative MP does not vote in any debate except when needed to break a tie. This takes the total number of working members down to 644.
And then there are the three deputy speakers. Lindsay Hoyle (Labour), Eleanor Laing (Conservative) and Dawn Primarolo (Labour) are bound by the similar rule as the speaker, and do not vote in any debate except when needed to break a tie. If we remove them from the total of working MPs, we’re down to 641.
This in turn reduces the number needed for an absolute majority in the House of Commons to 321.
Now of course removing the speaker and deputy speakers from the number of working MPs also removes them from the ranks of their respective parties. So while the Tories currently have a total of 304 MPs attending the Commons and Labour has 257, in practice they have 302 and 255 respectively.
But in a hung parliament, these differences matter. And they will again, should the UK end up with another hung parliament after the 2015 election. It was by exploiting this kind of arithmetic that the Labour governments of 1964-66 (initial majority: four) and October 1974-79 (three) were able to survive.
Should a government with a similarly small majority take office after the next election, or even a minority government a handful of seats short of the target, it will be upon such minute calculations that our country is run.