It was the journalist Aidan Kerr who first identified what he called “the Ulsterisation of Scottish politics” in late 2014. As long as voters cared either about independence or maintaining the Union, he reasoned, the constitution would play a large part in dictating where they placed their cross at election time.

So it proved, first in May 2015 and once again last Thursday. In Northern Ireland the Democratic Unionist Party and Sinn Fein still dominate its devolved Assembly as the main parties of Unionism and Nationalism respectively, a dynamic now reflected in the Scottish Parliament by the Scottish Conservatives and SNP.

And once politics is framed in such a way, my reckoning is it will be a long time before that changes. Indeed, as I’ve written before, it can only really change (or be resolved) once Scotland becomes independent or Ireland reunifies. And even then, as the history of southern Ireland illustrates, old tribal loyalties can take a long time to recede.

But here’s the thing, it’s also a dynamic of mutual benefit to the SNP and Scottish Conservatives. Nicola Sturgeon enjoys nothing more than railing against “the Tories” (two words she spits rather than speaks), while having established herself as someone who will “stand up” to the Nationalists, Ruth Davidson will relish giving as good as she gets.

Thus the terrain for the next five years is clear. As one SNP insider put it to the Sunday Herald: “It’ll be those folk [Tories] criticising the [SNP] government and attacking us. I can not wait.” Week after week the First Minister will frame the battle as between “progressive” Nationalism and “regressive” pro-austerity Unionism.

I can see the logic of that analysis but can’t help feeling the increasing autonomy of Scottish politics makes that scenario increasingly unlikely, for it applies the framing of “British politics” to the post-referendum landscape, and the notion of British politics, as most political scientists now agree, is now pushing up the proverbial daisies.

Think back to the recent Holyrood election campaign. Scottish Labour didn’t collapse because of Jeremy Corbyn (he was rarely mentioned) or even anti-Semitism (except perhaps in one constituency, Eastwood) but because the party, as the incoming MSP Anas Sarwar observed yesterday, appeared to voters as neither “comfortable Unionists” nor “comfortable Nationalists”. The result was that the more comfortable Unionist party – the Scottish Tories – increased its vote-share by eight per cent.

The British political backdrop to Ruth Davidson’s campaign was also consistently unhelpful: Tory civil war, uncertainty over ship-building contracts and a row about child refugees, yet come polling day it didn’t have the negative impact Ms Davidson was privately concerned it might, further proof the Ulsterisation of Scottish politics means what happens at Westminster now matters less and less.

New powers coming the Scottish Parliament’s way have also changed the terms of debate. Sure, at First Minister’s Questions each Thursday Nicola Sturgeon will have a pop at the Tories about London-imposed austerity and welfare cuts, but they’re now armed with a counter-pop: okay, they’ll say, you don’t like UK Government policy, so why don’t you use your new discretion over income tax and welfare to do something about it?

The Scottish Conservatives are also determined not to fall into that obvious ideological trap. Its recent manifesto for opposition was quite centrist, as the Tories north of the border have long been, while Ms Davidson has made a point over the last year or so of distancing herself from aspects of the UK party agenda.

In other words, she’s continuing a long-standing tradition of what the historian Graeme Morton called “Unionist Nationalism”, simultaneously celebrating the Union and Scottish distinctiveness. It’s always been a delicate balancing act (Margaret Thatcher, for example, never got the hang of it), but it’s now a requirement of modern Scottish politics: we’re all, as Peter Mandelson didn’t say, nationalists now.

As usual, there’s nothing new under the sun. Back in the 1920s – once British politics had been recalibrated by the secession of the Irish Free State – the old Scottish Unionist Party cleverly repositioned itself as a catch-all opposition to “socialism”, hoovering up old Liberal votes by being more moderate than the Conservative Party in England and Wales.

Now the Scottish Conservative and Unionist Party is doing the same thing in constitutional terms, and will need to be similarly moderate if it wants to hold on to the Liberal Democrat and Labour voters it gained last Thursday. Indeed, the logic of the Scottish Tory result is, paradoxically, that Ruth Davidson and her 30 MSPs will have to be more nationalist and operate increasingly independently from London, echoing SNP tactics in constructing as big a Unionist tent as possible.

The optics of Nicola versus Ruth (established, thanks to the BBC, during the final leaders’ debate) also plays well to Scottish Tory strategy. “Sturgeon has crossed a line and become like Alex Salmond,” reflects a senior Conservative of his experience on the doorstep, “much more Marmite, and that’s bundled up with opposition to a second referendum.” SNP activists also heard angry references to “that woman”, a rather misogynistic sobriquet once reserved for Mrs Thatcher.

Thus among some Unionist voters, as one veteran Tory activist put it to me, “hatred of the SNP trumped hatred of Tories”. But one mustn’t get carried away; the SNP is still in a powerful position with 63 MSPs and the Scottish Conservatives a stronger but still small opposition party with 31. As the First Minister keeps pointing out, her party “polled more votes than Labour and the Tories combined”.

Of course that is true, but it’s now just that little bit harder to depict Scotland as deeply anti-Tory (although doubtless that won’t put anyone off). It’s useful, meanwhile, from the SNP’s point of view to have both a Conservative bogeyman at Westminster and another occupying 31 seats at Holyrood.

Nevertheless, it feels to me that the SNP’s command of the discourse feels less secure than it was, opening up a narrative opportunity for the Scottish Conservatives centred on the question of another independence referendum: while the Scottish Tories are clearly against, the SNP continues to face both ways, an equivocal position that backfired during the election campaign and will now prove increasingly unsustainable given its lack of an overall majority.

Of course the last time the SNP were in a minority the Scottish Tories backed them on several crucial budget votes, co-operation both parties would now rather forget. This time they’ll have to play a cleverer game, pushing for committee reform in order to “hold the SNP to account”, perhaps with Murdo Fraser as the new Presiding Officer.

Yesterday the BBC’s Andrew Neil asked Ms Davidson if she believed a Scot could once again become Prime Minister of the UK. She replied that “talent will out” and that a future premier could even come “from Northern Ireland”. That, I’m afraid, is a fantasy, for Ulsterisation is now complete, not just in the six counties but in Scotland too.