Peter Duncan is Managing Director of Message Matters, and is a former MP and Chairman of the Scottish Conservatives.

The stakes could not be higher, and the consequences of failure do not bear thinking about for the two strongest women in UK domestic politics.

Theresa May and Nicola Sturgeon would probably not find much in common about their life stories, nor in their visions of the future and the kind of country we should aspire to, but they have more in common than they would admit. Their professional relationship might still be in its infancy, built upon that fragile first venture outside England when the Prime Minister climbed the steps at Bute House in Edinburgh, but it is entering a crucial new phase.

We can but hypothecate on the kind of relationship that would have developed between Theresa May and Alex Salmond, but Sturgeon presents a real challenge for the Prime Minister. Given the devastating level of Labour weakness, and as one of the nationalist movement’s most able minds, in many ways she has represented the leader of the opposition across the UK, the country she wants to divide permanently.

The calling of a general election has brought that contest into sharp new focus. However tempting and apparently low risk was the calling of the 8th June poll across the rest of the UK, there can be no doubt that it has further raised the stakes in Scotland.

Scotland has been, and remains, a country divided, and there is little evidence to suggest that this coming plebiscite (extraordinarily, the seventh vote in three years north of the Border) will do anything to heal that division. The Prime Minister was right to highlight that the country was coming together after Brexit, but perhaps wrong not to point out that in Scotland the chasm in public opinion is wider than ever before.

The two highest profile leaders in Scotland, Sturgeon and Ruth Davidson, will both now be signing off on campaign plans for 8th June that will emphasise that division. For Sturgeon, this will be another opportunity to highlight how the election of another Tory government at Westminster makes the case for Scottish separation more pressing than ever before. For Davidson, she will ably respond with a plea for all unionists to rally behind her cause and send a message of rejection to the SNP. Both are undoubtedly effective rallying cries, both will treat Labour and Lib Dem alternatives as a diversion, and the polarisation of Scottish politics will have been further cemented.

This Conservative strategy has opportunities and risks. There is no doubt that the election provides another chance to make further progress in electing more Scottish Conservatives than at any time in the last political generation. You would expect that seats along the Border, in Aberdeenshire and in Edinburgh and Glasgow will present realistic chances of success, with the number of Scottish Conservative MPs elected rising four, five or sixfold. There are some talented individuals that may well find themselves in the House of Commons on a rising tide of unionist opinion, including John Lamont and Ian Duncan – and that will be welcome reward for years of service to the Tory cause in Scotland.

Those most opportunistic of Conservative strategists will see the chance to rebuild alliances in traditional Conservative heartlands, with the return of those who in the ’80s peeled off to the Lib Dems in the Borders and the North East, and the tartan tories who deserted to the SNP across the Highlands and in the South West. The creation of a small and able band of Scottish Conservative and Unionists at Westminster will be welcomed, although the degree to which they have been elected as Conservatives rather than Unionists will be a matter of considerable interest, I’m sure.

However, this is not a risk-free game in Scotland. The very same strategy, of pushing this election as a referendum on the SNP’s ambition to have another vote on Scottish independence, does run the risk of rebounding on May after the result is declared.

There is little doubt that the SNP will elect fewer MPs in 2017 than they did in 2015, but arguably not that many fewer. Any result which sees the election of more than 45 nationalists to the Commons, in an election which the Tories themselves have positioned as a referendum on indyref2, will raise some awkward questions for the Prime Minister as she forms her new government. As David Cameron found out, if you call a referendum, and then lose it, there are consequences. The Prime Minister may find that there are political consequences in losing the general election in Scotland to the SNP, and pressure for another independence vote may become unstoppable.

In any case, whilst the timing is right for a general election, as May has made clear, it is already slightly awkward to recall that “now is not the time” for a second referendum on Scottish independence. “Now is not the time” is a line that will surely be stretched to breaking point after a general election.

Of course, whilst it may be that the further polarisation of Scottish politics will prove productive politically over the next six weeks, it cannot be in the interests of good government in Scotland. With Scots’ eyes on matters constitutional for the last fifty years, Scotland has slipped backwards. Our GDP per head is continuing to fall behind the rest of the UK, we build fewer businesses and our public services are slipping backwards. Perhaps the most unfortunate byproduct of this election is that it will return the nation’s gaze to the constitution, just when there was a chance of a real and productive examination of the SNP’s failures in office starting to impact on the electorate. That critique will be put on ice over the next months as the game theory of independence returns to centre stage.

Sturgeon knows that her task is simple. She must win the election in the overwhelming majority of constituencies in Scotland, and then win the PR war thereafter. There must be a perception that electing (say) 45 nationalists represents a great victory, rather than the loss of a handful of seats to the Tories and perhaps the Lib Dems being a devastating setback from their 2015 political “earthquake”.

These are high stakes. Who knows what effect another crushing defeat for Labour, and a new three-figure majority for the Prime Minister will have on remaining Labour voters in Scotland. Will they see the merits of playing the long waiting game for a change at UK level, or will they like the short-term opportunity to end Tory rule that a second independence referendum will present? The SNP, and more particularly Sturgeon, knows that therein lies the key to her future – either a new, majority-supported, left-leaning movement for independence, or another referendum defeat ending nationalist hopes for the long-term. May must also know that her future prospects as Prime Minister are hopelessly intertwined with those of the Scottish First Minister.

This is a general election with little at risk, beyond the Union itself.