The professor will see you now - majority envy

4 min read10 February

In an occasional series, Professor Philip Cowley offers a political science lesson for The House’s readers. This week: majority envy

“We’ve got a massive majority.”

At least that’s what I heard the Prime Minister say at PMQs on 22 January – although for some reason Hansard records it as “we have massive [sic] majority”. But how massive?

You’re an informed bunch, so you don’t get any points for knowing the difference between the raw numbers and the actual working majority, once you factor in the non-voting Speaker and his deputies plus the non-sitting Sinn Féin MPs. At the time of writing, the latter is 163.

That’s lower than it was just after the election, but it’s still larger than the majorities enjoyed by every single post-war prime minister except Tony Blair’s first two parliaments between 1997 and 2005.

But here’s a tougher question: how big has the government’s majority been in actual votes in the House of Commons since the election?

It varies, of course, from day to day and division to division – but in the first 91 whipped votes of this Parliament, the government’s majority has averaged a whopping 238. It’s even more massive in reality than it seems on paper.

Compare that with the early days of the Blair administration: the average majority in the equivalent first 91 whipped votes then was 214. So even though the Blair administration had a larger majority on paper, its majority in practice was smaller than that of today.

There are several reasons for this, but a key part of the explanation is to be found across the aisle from the government. The 121 Conservative MPs elected last year constituted a record low dating back to 1832. They were elected alongside a total of 117 other opposition MPs who were not Conservative; a post-war record. In 1997 Conservative MPs outnumbered the rest of the opposition by more than 2:1; now it’s almost 50/50.

Another way of looking at this is to employ a measure called ‘the effective number of parties’. This has been used by political scientists to measure the fragmentation of a party system ever since it was first created in 1979.

To calculate it, you divide one by the sum of the squared proportions of the vote or seats gained by each party. This is easier in practice than it sounds when described in the abstract. If Labour had, say, 40 per cent of the votes, the Conservatives 50 per cent and the Lib Dems 10 per cent, you would square each of .4, .5 and .1 (producing 0.16, 0.25, and 0.01), add the resulting figures together (0.42), and then divide one by that total (1/0.42=2.38).

This produces a measure of party fragmentation, taking into account both how many parties there are and crucially – because this is one of those areas of life where size really does matter – how large they are.

The overall effective number of parliamentary parties is no larger now than it was 50 years ago. But if we look just at the opposition, in the whole of the post-war period the effective number of opposition parliamentary parties has varied between just over 1.00 and just under 2.00. The figure for 2024 was a record-breaking 2.82.

This has a number of consequences, most obviously when it comes to voting – because it is difficult to find issues around which the varied interests and beliefs of a fragmented opposition will coalesce.

Since the election, the Conservatives and Lib Dems have only been in the same division lobbies in marginally over a third (35 per cent) of votes. And even when they do vote together, there is no guarantee that every other opposition party joins them.

And remember that for the government to get into serious trouble requires more than just the opposition to be united. It also requires a significant number of Labour MPs to defy the whip. That needs an issue which somehow unites the Conservatives, the Lib Dems, Reform UK, the Greens, the independents, and the Northern Irish parties and a decent chunk of Labour MPs.

Further reading: M Laaskso and R Taagepera, “Effective” Number of Parties: A Measure with Application to Western Europe, Comparative Political Studies (1979)

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