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Scotland’s 46 marginal seats create election thrills, but can Tories defend 2017 gains against resurgent SNP?

Any election brings a flurry of news stories highlighting the marginal seats to watch out for. And in Scotland there are a glut this time around. Last time, 2017 saw an election night of very close calls, none more so than North East Fife where the SNP’s Stephen Gethins squeaked home by just two votes. In the end the SNP lost 21 seats and the Scottish Conservatives gained 12 seats, eclipsing Scottish Labour as the main party of opposition.

The table below shows what an unusually bumper crop of marginals there are in 2019. Seats are classified according to how many percentage points the winner was ahead of the runner-up. Going into the 2015 election, 33 out of 59 Scottish MPs had won their seat by more than 20 percentage points, and so were safe barring a swing of at least 10 points to their challenger. Going into the 2019 election, only two – Labour’s Ian Murray in Edinburgh South and Conservative John Lamont in Berwickshire, Roxburgh and Selkirk – enjoy that relative security. No fewer than 46 MPs are vulnerable to a swing of five points or less.

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So a thrilling election night is in prospect, then, with sitting MPs toppling right, left and centre? Well, not necessarily. The connection between the safeness of a seat and the chances it will change hands is much looser than we might expect. There was one vivid illustration of this in the 2015 election when nine out of 10 of those supposedly “ultra-safe” MPs were swept away in the extraordinary SNP surge from six to 56 seats. But the point holds in less unusual elections, too.

The left-hand side of the graph below shows, for the 2017 election, how many seats in each category were held and how many were lost by the incumbent. While there is a tendency for safer seats to mean safer MPs, the connection is indeed loose. Plenty of safe seats are lost, and plenty of marginal seats are held. While only nine seats going into that election would have been regarded as marginal, 21 changed hands – all lost by the SNP to one of the unionist parties.

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Swing time

The YouGov MRP projections for Scotland predict that just eight seats will change hands. The large majority of even the most marginal seats appear likely to be retained by incumbents in what looks like being a less stressful election night than many will have feared. In theory, Scotland has many fewer safe seats in 2019; in practice, those seats look a lot safer than they did in 2017.

The explanation is not hard to find. Large swings between the parties render even “safe” seats unsafe, while small swings mean that even marginal seats are largely unaffected. In the 2010 general election in Scotland, there were swings of just a couple of points between the four main parties and the upshot was a highly uneventful election night, with literally no seat changes compared to the previous election in 2005.

It also matters whether any swings are predominantly to or from the party that happens to hold many marginals. Seven of the 10 most marginal seats going into this election are held by the SNP. They look much less vulnerable when we consider that that party is polling at several points ahead of its 2017 showing. Four of the seven look even less vulnerable given that they were won ahead of Labour, whose poll rating has plunged.

Then we have to factor in that swings between the parties might be different across Scotland. In fact, they are highly likely to be, given the prominence of Brexit in this election and keeping in mind the popularity of Brexit varies quite a bit across Scotland.

The table below is based on the eight Scottish parliament regions. It shows the estimated Leave vote (based on election expert Chris Hanretty’s widely used estimates) and the estimated net swing from the Conservatives to the SNP (based on the YouGov MRP estimates). Not surprisingly, the more Leavers there are in a region, the better the “get Brexit done” Conservative vote holds up against the “stop Brexit” SNP.

Note: these figures are approximate given that Westminster constituencies do not map perfectly onto the Scottish Parliament regions. Author provided

So, although the SNP’s 2017 victory over the Tories was narrower in the Lothian seat of Edinburgh South West (2.2%) than in the Highlands & Islands seat of Argyll & Bute (2.8%), it is only the latter that looks even vaguely competitive in 2019. The swing against the Conservatives in the Remain-land of Edinburgh rules them out of contention.

Election thrills and spills

Where does all of this leave us? Answer: looking in different places for excitement on election night. The table below shows two different lists of Scotland’s 10 most marginal seats. The left-hand list is the conventional listing, headed of course by North East Fife. The right-hand list is based on those MRP estimates of vote shares for each party in 2019, which can be used to predict what will end up being the closest races on the night.

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North East Fife is the only seat that appears on both lists. This underlines the point that the swings between elections can change the picture completely, turning marginals into safe seats and vice versa. Take Glasgow South West, won by just 60 votes in 2017 but projected by YouGov to see a 17-point SNP win in 2019. By contrast, the Tories have a majority of nearly 5,000 in East Renfrewshire but YouGov bills it as a “toss-up” – and one that the SNP, much helped by this being Scotland’s third most Remain-friendly seat, are fancied to take.

The central narrative of this election night in Scotland will be how far the Conservatives can defend their 2017 gains against a resurgent SNP. In light of that, it is notable that five of the 10 most marginal seats in the right-hand list feature exactly that battle. All five are currently held by the Tories but they are not only on the defensive in this election. The party looks to be within striking distance of SNP incumbents in Lanark & Hamilton East, Argyll & Bute, and Central Ayrshire.

There is a rural flavour to the right-hand list of likely marginals. With the SNP dominating the urban central belt, it is in the Leave-friendlier rural areas that the Conservatives can compete. These sprawling rural seats often mean slower declarations, for logistical reasons that may prove even more pertinent in a December election. If you want to see Scotland’s closest electoral races won, settle in for a late one.

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