Pinterest WhatsApp

The polls in Scotland just before the last election showed a 21-point lead for SNP over Labour. The SNP went on to take all but one of Labour’s 41 Scottish seats.

This week Theresa May called a general election in the wake of polls showing her Conservative party 21 points ahead of Labour. Could Labour now be headed for a Britain wide meltdown of the kind that they suffered in Scotland two years ago?

Intriguingly, the distribution of the 2015 Labour share of the vote across the seats they are defending now is very similar to the distribution of their 2010 share of the vote in the Scottish seats that they were defending in 2015. In both sets the vast majority of seats involve Labour defending vote shares of between 40 and 65 per cent with an average of 50 per cent. In Scotland two years ago, the largest share that they were defending was 68 per cent. This time Labour have a dozen ultra-safe seats with shares bigger than 68%. That will be little comfort for them.

But it is not the share of the vote that matters so much as the lead over the Conservatives that are defending. In Scotland last time they lost seats where there had been majorities all the way up to 54 per cent. Now Labour have just 13 seats with leads over the Conservatives greater than this. Not much better.

The SNP might have taken even “safer” Labour seats had there been any. Some of the largest swings from Labour that the SNP achieved in 2015 are big enough to unseat any Labour MP if the Tories achieve the same at this election.

So is it reasonable to expect a major meltdown for Labour this time?

Not really. The Tories may be going into this election with a similar lead over Labour that the SNP had at the last election, but it is not the lead alone that matters. It has to be understood in the context of the distribution of votes across seats.

The SNP managed to win nearly all the seats in Scotland with just under half the votes because the votes against them were spread out between several parties, at the local as well as the national level. This led to a very efficient distribution of the vote for the SNP. In the seats the SNP won the average margin of victory was 20 points, less than the 25-point average for the Conservatives. Not only did the SNP not waste so many votes building up bigger majorities than necessary to win, but by only losing three seats they barely wasted any that way either.  By contrast, 26 per cent of Conservative votes in 2015 were in seats that the party lost.

This difference in efficiency was anticipated in advance and largely the product of the distribution of votes in 2010. It was clear from uniform change projections from the Scottish polls in 2015 that Labour were going to lose nearly all their seats.

At the moment GB polls are pointing towards a 6-point swing, or so, from Labour to the Conservatives. That translates to Labour losing about 50 seats with uniform change projections. They would still retain about 180 because of the distribution of votes. That would amount to their worst performance since 1935 but still Labour are in a far more secure position in England and Wales than they were in Scotland two years ago.

Since swing is never actually uniform a key question at this election is whether there will be any pattern in the variation in the swing across constituencies that might either limit or extend the scale of Labour losses. Here there are important lessons from both Scotland last time and Labour’s experience at the 2010 election. I am hoping to write about them in further blog posts soon. Some are comforting and some worrying for Labour. None are as important for Labour as trying to reduce or even reverse the apparent swing against them before election day.


 This article was first published on the Elections Etc. website.



Previous post

"Strong leadership needed for Brexit negotiations" Will this framing of the early election work for Theresa May?

Next post

Estimating the Effect of Feature Selection in Computational Text Analysis