At first glance Scotland would appear to be a sideshow in the battle to determine whether Boris Johnson or Jeremy Corbyn spend Christmas Day as the tenant of 10 Downing St.

Most of the country’s Westminster seats are held by the SNP, who have no prospect of forming the next UK government. Meanwhile there is not a single Scottish seat where Labour and the Conservatives share first and second place and thus are competing directly with each other.

Yet nowhere will be more keenly contested at this election than Scotland. For it would take little for Scotland’s political landscape to be transformed. The 2017 election left the country littered with marginal seats. The winner’s majority was less than ten points in no less than 46 of the country’s 59 constituencies.

That means the SNP’s dominance of Scotland’s representation at Westminster is potentially highly vulnerable. As many as 30 of the 35 seats the party currently holds are marginal, with Labour the principal challenger in as many as 22 of them.

Conversely, a small swing in the nationalists’ favour could see the party reverse many of the losses the party suffered two years ago.  Eight of the 13 seats won by the Conservatives last time are marginal, as are six of the seven seats that Labour captured. So also a couple of those won by the Liberal Democrats. 

The outcome in these marginal seats matters a great deal to both the Conservatives and Labour. 

In 2017, the 13 seats the Conservatives won north of the border were crucial to Theresa May’s ability to form another government. Without them, the deal she struck with the DUP would have been insufficient to give her a majority. Now, for every seat lost north of the border Boris Johnson will need to win one in England or Wales just simply to stand still.

Meanwhile, any hopes  Labour might have of winning an overall majority at Westminster are unlikely to be realised if the party does not recapture many of the seats the party first lost to the SNP in 2015. 

If the party recaptured all of the 22 marginal seats where it is second to the SNP, Labour would need just over a three-point swing from the Conservatives in the rest of the UK to win an overall majority. However, in the absence of any advance north of the border, the party would need as much as a six-point swing in England and Wales, a much more challenging target indeed.

Yet it would appear that both the Scottish Conservatives and Scottish Labour could well be on the defensive at this election. Separate Scotland polls have been thin on the ground in recent months. 

The most recent, conducted in mid-October by YouGov, put the SNP on 42%, up five points on 2017, while the Conservatives were on 22%, down seven and the Liberal Democrats, 13%, up six points. Meanwhile, Labour, on 12%, were not only reckoned to be as much 15 points down on two years ago, but were put in fourth place.

Such an outcome would see every single marginal Conservative and Labour seat fall into the SNP’s hands, leaving the SNP with as many as 50 seats. The Conservatives would have just three and Labour, one. Five seats would be won by the Liberal Democrats.

However, the Conservatives’ position in Britain-wide polls has improved during the last month, while Labour has made some progress too. 

Both parties thus have grounds to hope that their position north of the border will not be as dire as suggested by YouGov, even if much of the Conservative advance has been achieved among Leave voters who are relatively thin on the ground north of the border. 

Indeed, a look at the figures for Scotland in recent Britain-wide polls suggests that the recent Conservative advance is in evidence north of the border too. During the last week six polling companies have published detailed tables that include separate figures for Scotland. 

In those polls the Conservatives are on average on 26%, down just three points on 2017, although, at 17%, Labour are still down by as much as ten points. These same polls suggest that the SNP, on 38%, might be doing little more than holding their own, while the Liberal Democrats are credited with 11%.

These figures should be treated with care – they are not as robust as a properly conducted separate Scottish poll. 

Nevertheless, they suggest that a rather more favourable wind may now be blowing through Scottish Conservative sails, enhancing the party’s prospects of retaining most of the seats the party is trying to defend - and so contribute to a Westminster Tory majority. 

However, for Labour there appears to be little comfort. Scotland looks set to make Jeremy Corbyn’s chances of winning an overall majority very low indeed.

John Curtice is Professor of Politics, Strathclyde University and Senior Research Fellow, ScotCen Social Research and ‘The UK in a Changing Europe’