IT may seem a trite observation, but this most unexpected of Westminster General Elections represents both an opportunity and a threat for the pro-independence movement. Recent polling of Westminster and Holyrood voting intentions suggests that the SNP are currently only a little below, or perhaps even a little above, the astonishing 50 per cent share of the vote they received at the last General Election in 2015.

If Nicola Sturgeon makes a virtue out of necessity by seeking to use the snap election to emphatically underline the mandate she already possesses for an independence referendum, there can be little doubt that the first-past-the-post electoral system will helpfully deliver a second consecutive overwhelming majority for the SNP in terms of Scottish constituency seats.

That’s the opportunity, but of course the nature of the UK’s “equal partnership” is that the rules for what constitutes a mandate seem to be radically different north and south of the Border. To be lauded as a successful leader, Theresa May simply needs a majority of seats, which is just as well for her sake because there is precious little chance that she will receive an absolute majority of the UK-wide popular vote. By contrast, the London media and political establishment will doubtless seek to impose all sorts of additional tests on Nicola Sturgeon.

It will be absurdly argued that any net loss of seats from the high of 56 achieved two years ago will detract from her mandate. The same claim will be made if the SNP fall short of 50 per cent of the vote. Therein lies the threat.

Recent history suggests that it’s not completely impossible that the SNP will smash through the 50 per cent barrier, but that it’s pretty unlikely. Even in 2015 they didn’t quite pull it off – their vote was reported to be exactly half, only after being rounded up by the tiniest of tiny fractions. At last year’s Holyrood election, an absolute majority of votes seemed a real possibility for a long time, but the effect of gravity kicked in with a vengeance as polling day approached. However, a majority of votes for all of the pro-independence parties combined looks considerably more realistic – it was actually achieved in 2015, and opinion polling suggests there may be a roughly even chance of it happening again. For example, a Panelbase poll of voting intentions conducted in March put the SNP on 47 per cent, and the Greens on 3 per cent.

The string of surprise election results we’ve seen in recent times should serve as a warning that nothing is completely set in stone as far as seat numbers are concerned. Nevertheless, the strong likelihood is that the SNP will find themselves seeking to minimise their losses, as opposed to holding absolutely everything they have or making a small net gain. The core Unionist vote has now coalesced around the Tories in a way that hadn’t even begun to happen in 2015, so it seems probable that there will be modest SNP losses in areas of traditional Tory strength, just as happened in the Holyrood election.

That said, first-past-the-post elections are different in the sense that parties can afford to heavily concentrate their resources on a small number of battleground constituencies. If, for instance, the SNP calculate that Calum Kerr has built up enough of a personal vote to have a realistic chance of defending his incredibly vulnerable 328-vote majority over the Tories, they will pour people and money into Berwickshire, Roxburgh and Selkirk, meaning that the outcome could end up being somewhat different than if nature had run its course.

IT’S a kind understatement to say that the Scottish LibDems are starting this election from a low base. It seems unlikely that things will get even worse for them – having had a near-death experience in their northernmost stronghold two years ago, it appears that Orkney and Shetland has reverted to being a relatively secure seat.

Willie Rennie and his colleagues can therefore set their sights on making a mini-comeback on the mainland at the SNP’s expense. They were actually more successful than other Unionist parties in remaining competitive in several constituencies at the 2015 election, leaving seats such as East Dunbartonshire and Edinburgh West firmly within striking distance if there is any boost in the amount of Unionist tactical voting.

For Scottish Labour, the prospects are relentlessly grim. Even amidst the disaster of 2015, they still won almost a quarter of the popular vote, ensuring that a new post-war low is now a racing certainty.

Opinion polls currently have them languishing in the mid-teens. They do have a good chance of retaining their sole seat in Edinburgh South with the assistance of Tory supporters, but whether that minor solace will be enough to sustain Kezia Dugdale’s position is open to question. It’s the last thing on anyone’s mind at the moment, but one of the most immediate effects of the local elections and the General Election being held so close together could be a third change of leader for Scottish Labour in the space of three years.