AND there we were, imagining this election was about Brexit.

Nicola Sturgeon has other ideas. Launching her party’s manifesto, she insisted that a vote for the SNP on December 12 was a vote for a second independence referendum. (And a vote to stop Boris Johnson, and a vote to escape Brexit.)

Can the result in Scotland really be interpreted as a clear signal that Scots want the chance to vote for independence, within a year? Of course not. As Ms Sturgeon knows, the issues of Brexit, independence and party loyalty cut across one another. Plenty of voters groan at the thought of another independence poll but will vote tactically for the SNP because they are appalled by Brexit and Mr Johnson, just as many SNP supporters will cast their vote for Ms Sturgeon even though they want out of Europe.

An Ipsos/MORI poll released yesterday showed that Scottish voters see Brexit, not independence, as the most important issue. Brexit is the number one topic even among SNP voters and it’s a nonsense to try and use this uniquely complex general election as a barometer of support for independence.

But luckily for Ms Sturgeon, acting Scottish Conservative leader Jackson Carlaw seems intent on framing it the same way. “It could not be clearer,” he insists, “that every voter who wants to stop Nicola Sturgeon taking us back to another referendum, perhaps within a year, needs to lend their vote to the Scottish Conservatives.”

The Tories’ opposition to so-called indyref2 is sincere, but will it be enough to repel independence? Short answer: no. Indeed, anyone imagining that a vote for the Tories makes independence less likely, needs to think beyond the next 12 months. The irony is that it could well be Tory votes in this election that lead to the break-up of the UK.

If you take the longer view, Boris Johnson’s opposition to another referendum is not actually the decisive issue. Far more important is the impact a Tory government could have on support for independence over the longer term, and that could be profound.

The Conservatives are significantly more likely than Labour to adopt policies, not least a damaging hard Brexit, that boost support for independence.

Remember that this time next year, at the end of the Brexit transition period, we could once again be staring down the barrel of a no-deal Brexit. We could be hearing that environmental and food standards regulations are being sacrificed on the altar of an American trade deal. Voters who have placed their faith in a serial liar to protect the NHS from acquisitive American companies, might be finding out how much his promises are worth. A few years later, and the economic impact of Brexit will be buffeting the whole country. Brexit plus economic downturn equals discontent, and discontent invariably leads to clamour for change.

READ MORE: Iain Macwhirter: Why many Scots will bite the bullet and vote for the Tories 

Cast your mind back five years. Strategists for the new SNP leader Nicola Sturgeon did not want another referendum until they were sure independence commanded 60 per cent support for an extended period. They surely still don’t, knowing that a second Yes failure would be catastrophic, and a narrow win nightmarishly divisive. Ms Sturgeon has been jostled into demanding one too soon in order to placate her supporters and shore up her own position.

A Boris Johnson government allows her to follow the strategy she always wanted. She can spread her hands in apparent despair that he won’t allow a vote while building that crucial support for independence by encouraging discontent with Westminster, in readiness for the poll when the numbers are right.

This is, admittedly, a counterintuitive argument. Given the Tories’ loud and unwavering opposition to another referendum in all circumstances, it might seem to opponents of independence like the safe option to back them.

But consider how well that strategy worked for the Conservatives when they tried it once before.

John Major’s ministers stuffed their fingers in their ears over a devolution referendum in the 1990s, when the people of Scotland wanted one. We all know what happened when that vote finally came.

It will be morally indefensible for the Conservatives to block so-called indyref2 if the pro-independence parties win a Holyrood majority in 2021 after fighting the campaign on that basis (even David Mundell concedes that). That does not appear to bother Boris Johnson, but with Labour having conceded the point, the Tories risk being isolated like they were under John Major. The Scottish Secretary Michael Forsyth was portrayed by Labour and the SNP as a high-handed tyrant, oppressing the peasantry.

READ MORE: YouGov Poll: The Scottish seats predicted to change hands at the general election

Lo and behold, the peasants revolted.

By the time the Conservatives have caved in and, like David Cameron, approved a referendum, or (more likely) crashed out of office making way for a Prime Minister who will, their obstinacy will have boosted Ms Sturgeon’s cause still further.

Recent machinations about the timing of a second independence referendum have tended to obscure a critical point: that holding a referendum does not guarantee independence. The SNP’s habit of trying to make independence seem inevitable is a tactic, nothing more.

For sure, the pro-UK parties have to have an attractive offer for voters, which may explain the Tories’ unwillingness even to have the argument. But against the backdrop of a Labour government at Westminster, the chances of a yes vote recede.

In the event of a radical left-wing Labour government mainlining cash into the NHS, focusing its policy effort on the post-industrial areas that were its former heartlands, and implementing a second Brexit referendum with a hard Brexit taken off the table, then the push factors driving former No voters towards independence would diminish. The campaign itself could be difficult for the SNP, faced with thorny questions about national debt, currency and public spending constraint.

In those circumstances, Scots might well choose to remain in the UK, especially given the experience of Brexit, which has already demonstrated how hard it is to negotiate even the basics of a divorce agreement.

What many independence campaigners miss, in their enthusiasm, is that securing agreement to independence from fellow Scots is a long game. Go to a vote too soon, and the cause is lost. The recent slight uplift in support for independence is nowhere near enough to make a Yes vote likely, and a Labour government won’t help.

But a Tory one might.