In a previous article, I outlined how the Scottish Conservatives could build on their remarkable performance on Thursday by examining a list of 13 constituencies where the Tories might plausibly challenge the SNP incumbent in one or two elections’ time.

Building up in those seats is half the challenge. The other half is doing so whilst resisting the temptation to collude in isolating the Scottish political system from the rest of Britain.

Commentators like David Torrance are apt to say that the concept of ‘British politics’ is dead, and it is certainly struggling.

In this article he remarks on how Scottish politics following the Northern Irish pattern makes a “fantasy” of Ruth Davidson’s claim that a Scot – or indeed, and Ulsterman or woman – could be Prime Minister.

In another piece, he quotes a Tory MSP who claims that the Scottish Conservatives “need to continue to distance ourselves from London” – i.e. actively collude in the ‘Ulsterisation’ process.

This instinct must be strenuously resisted, for whilst it may deliver short-term gains it is bad for the Union and for Scotland, and very difficult for the Tories to actually pull off in any event.

If our country is not to end up being completely hollowed out into a sort of skeletal alliance, it needs national politics and national parties. Unionists have had to compromise a lot in the devolutionary era, but they should have higher ambitions than there mere, technical survival of the Union.

The benefits of union flow from pooling our resources, human and otherwise. Davidson is right to want Scots and Northern Irish to be able to serve in the highest office – it should be a basic tenet of unionism that they can.

But this cuts both ways: Scots can only play a meaningful role in Britain if Britain plays a meaningful role in Scotland. If you allow ‘Home Rule’ to pare the Union down to foreign relations and defence, it is inevitable that the posts of Foreign and Defence Secretary will be the highest to which those from some Home Nations can aspire.

Ulster itself provides the warning. The creation of Stormont – against the express wishes of the far-sighted and sincerely unionist Sir Edward Carson – has served neither Northern Ireland nor Britain well.

We have been denied the contributions which Northern Irish politicians might otherwise have made to national life, and they have exchanged broadly effective national governance for first an oppressive Protestant ascendancy and then an ineffective and rigidly polarised legislature.

It would be a tragedy, and a disaster for the Union, if devolution were to cut Scotland out of national life as completely as it has Ulster.

This is especially true because Northern Ireland’s political system was mutated by the fact that for too long every election was a border poll by proxy. Almost two decades after the Good Friday Agreement the realisation is slowly breaking that the ‘referendum lock’ on the constitution removes the old imperatives from normal politics.

This has started to produce more political diversification on the Catholic side (where Sinn Fein and the SDLP are both in gentle decline), and waning turnout by Protestants who’d turn out to vote for the Union but are otherwise uninspired by the DUP’s old-fashioned, iron grip on unionist politics.

It would be doubly unfortunate if Scotland fell into the polarising, paralysing and wholly unnecessary dynamics of Ulster politics just as Northern Ireland itself began to move on, especially as nobody benefits from polarising politics around the constitution as much as the SNP. The referendum requirement gives you room to breathe, and to look beyond the constitution in your day-to-day politics.

But even if the Scottish Conservatives were minded to become ‘Unionist nationalists’ in the mould of the DUP, their current arrangements preclude it.

If last week’s successes translate into gains at the general election, there will be a group of Scottish Tory MPs. Unlike the DUP they won’t be tucked away in comfortable impotence on the ‘Others’ benches, but taking the Conservative – likely the Government – whip.

That means taking ownership of national policy, not trying to have one’s cake and eat it by setting your own (as even Davidson seemed to try, to a small extent, in 2015).

Even Murdo Fraser’s plans for a separate ‘sister party’ included a joint Westminster caucus (unless you listen to Andy Maciver, who helped run his leadership bid), and Davidson was elected on a platform of rejecting that plan.

The Scottish Conservatives are Conservatives, and part of the UK-wide Conservative and Unionist Party. They must never forget why this is important, or stop striving to succeed as a British party as well as a Scottish one.