One of the supposed merits of the UK’s first-past-the-post electoral system is that it delivers strong governments – that is, it gives disproportionate representation to bigger parties, which until 2010, tended to ensure that one of them had an overall majority.
This is why smaller parties don’t like it. The Liberal Democrats have always been against it and as part of the coalition agreement in 2010 they secured a referendum on switching to an alternative vote (AV) system. After some quite strident campaigning against this change from the Prime Minister among others, the public voted pretty decisively against, condemning smaller parties to many more years of under-representation.
But not all smaller parties. There is one smaller party that is set to get a huge bonus in May thanks to first-past-the-post, ending up with twice as many seats as it would under a proportional system. That party is the SNP.
According to the latest projections on may2015.com, the nationals are set to get 4.08% of the vote in Great Britain, but claim 55 seats, or 8.46% of the total. This is because first-past-the-post doesn’t just favour big parties – it also favours those that are more geographically concentrated.
We can see how this works by building a simple model that distributes a given vote share across different geographical areas, with some random fluctuations and a fixed victory threshold. The chart below shows the number of seats that the model predicts for parties concentrated on Great Britain, England and Scotland, compared with the projected results of the major parties. Although the model is crude, it matches up pretty well with these projections.
How many seats a party would win for a given share of the Great Britain vote, by geographical coverage, and the latest projections from may2015.com for the main parties
With votes spread evenly across the whole of Great Britain (think Labour and the Conservatives) you need quite a large share before you are likely to win any seats at all. If you are concentrated in England only (think UKIP) the threshold is a bit lower, but it’s still looking tough with anything less than 20% of the vote. Smaller parties mainly focused in certain areas of England (like the Lib Dems) do a bit better. But if you are entirely concentrated in Scotland, you can get a decent number of seats in Westminster with a tiny proportion of the total vote.
The SNP presumably like the first-past-the-post system now, but ’twas not always thus. In 2011, in the run-up to the AV referendum, a party spokesperson said:
Faced with a choice between the fundamentally unfair first-past-the-post system and a step towards a more democratic system, the SNP’s National Executive has agreed that the SNP will support a Yes vote in the AV referendum.
At that time the SNP were small even in Scotland and had just 6 seats. But now they are big in Scotland – they are projected to get 48% of the Scottish vote – and are forecast to cash in with a whopping 55 seats. Will they use their newfound influence to continue their push for electoral reform?
Contrast this with the fortunes of UKIP, who command much greater support overall and are expected to win more than three times as many votes as the SNP, but will walk away with a measly 5 seats. All of which goes to show that you don’t need to be a big party to reap the benefits of the first-past-the-post system, you just need to be big somewhere.
If the SNP do go on to win this number of seats, and if the Union and our parliamentary system survive the arrival of the Nats in Westminster, could this have consequences for other regions? If localised parties can secure a good share of the vote in one region, they can secure disproportionate representation in parliament and use it to push local issues / sabotage the union from within / whatever else they want to do. The London Party anyone? (We are the richest region in Europe and it’s time we stopped subsidising the rest of the country!) Or perhaps the Cornish Assembly, or the People’s Front of Tyne and Wear?