There is, of course, always a purpose in any Prime Ministerial visit and Boris Johnson's trip to Elgin today is meant to help Scottish Conservative candidates in the north-east see off an expected charge from the SNP on December 12.

A fall in support, even by quite modest levels, could see the loss of some of the party's 13 Scottish seats, a move that would make winning a majority throughout the UK that much harder.

A quick look at the psephology tells you why the Conservative leader might be worried.

In Moray, where the Prime Minister was today, a swing of 4.4% to the SNP would unseat Douglas Ross. In Banff and Buchan a 4.5% swing would see the seat fall to the SNP whilst in Gordon a mere 2.5% swing would put an end to Colin Clark's political career. The stakes are high and the electioneering on the ground in these constituencies will be particularly intense.

Elsewhere, the Tories look to have some breathing room in West Aberdeenshire and Kincardine with the SNP requiring a swing of almost 8% to take the seat. The challenge in Aberdeen South appears less daunting for the Nationalists with a swing of 5.4% needed to take a seat where the Conservative MP since 2017, Ross Thomson, has stood down following allegations about his behaviour in a House of Commons bar.

The polls - limited as they are in Scotland - show that the SNP is recovering ground lost at the 2017 election. In 2015, all of the aforementioned seats were won by Nicola Sturgeon's party.

Just to complicate matters the Liberal Democrats have a spring in their step and expect a 'Brexit bounce' at the polls as the memory of their coalition with the Conservatives fades. Or so they hope.

Gordon and West Aberdeenshire and Kincardine (admittedly with different boundaries) have been held by the Lib Dems in the past, so an increase in their vote this time around begs a simple question, where are the new votes coming from? It's a factor, perhaps a critical one, that adds to the intrigue.

On election night the north-east battleground will be fascinating. If the Tories hold on, the object of winning an outright majority in the UK will be made easier.

Wins, however, for the SNP will pile more remain-supporting MPs into the next parliament and increase the possibility that Boris Johnson's Brexit deal could go the same was as some of his candidates in the north-east.