Yesterday, Nicola Sturgeon unveiled a proposal to devolve certain aspects of our post-Brexit immigration policy to Scotland. Well, you might say, she would say that, wouldn’t she? But Sturgeon’s argument has some merit, for Scotland has a demographic problem that is not shared by the rest of the United Kingdom. A few thousand Scotland-only visas issued each year has the potential, assuming they proved sufficiently attractive, to address that.

This is not just an SNP ploy, either. There is a widespread acceptance in Scotland that the country needs to be able to do more to attract more immigrants. On current trends, immigration is likely to be essential for the population growth Scotland is likely to need. As matters stand, there are already a serious and debilitating number of vacancies in key sectors like health and education. Agriculture also has particular needs and farming is a more important - if still relatively minor - part of the Scottish economy than the UK’s as a whole.

In the grander scheme of things, it matters little whether new measures are instigated by the UK government on its own or on the prompting of the Scottish government. For their part, there is a tentative acceptance from the Scottish Tories that Scotland, here as in other areas, does actually have different interests from those of the UK as a whole. If Unionism cannot accommodate those differences, it loses the flexibility upon which it has always depended and by which, indeed, it has been defined in its better moments.

Scottish business organisations are also broadly on board with the idea of a bespoke immigration system north of the border. Nor is this beyond the wit of man. There is ample precedent for regional (in this case national, obviously) visas and work permits to be introduced. It can and has been done elsewhere; it could be done here too. The existence of a specific Scottish tax code removes some of the complications that would previously have hindered such a policy.

But rather than consider the Scottish government’s proposals, the UK government waited no more than an hour before reminding Edinburgh that 'immigration is a reserved matter'. Well, yes, everyone knows this, so thanks for that.

If, as Boris Johnson avers, he is to be a 'One Nation' prime minister then he is going to have to take some account of and pay some attention to the idiosyncrasies of the nation he leads. The United Kingdom is a hybrid-state, sometimes unitary sometimes very far from being so and that requires a prime minister to possess a certain flexibility. This is one of those occasions where recognising distinct differences is a sign of strength, not weakness.

At the very least, there is little lost - and perhaps something gained - from being polite. You may suspect that the SNP are always on manoeuvres but there is a difference between saying 'no' to the SNP and saying 'no' to Scotland. Just as it is wearisome when the nationalists conflate party and country, so it is a mistake for the UK government to do likewise. At present, Johnson’s administration appears to be in danger of doing just that.

Listening to Scottish concerns and, heavens, even on occasion engaging with them might not deliver the visceral thrill of an abrupt 'No' but it is more likely to pay a dividend than immediate, instinctive dismissal. Sure, some Scots, perhaps as many as one in three, will lap such stuff up. But the middle ground of Scottish politics - which is also, it should be said, the determining ground - finds that pose less appealing. Those questioning Scots have not yet been pulled to independence by Edinburgh, but they could be pushed towards it by London.

Dismissal of this sort forgets that, for the most part, even Unionists are Scots first. The dam will not break yet but the pressures on it remain considerable without the UK government weakening, or failing to repair, the structure still further.

Perhaps Johnson’s government will add an additional weighting for immigrants keen to come to Scotland if, or as and when, it introduces its ballyhooed 'Australian-style points system'. As matters stand, that seems the least it can do. A failure to take account of different realities in different parts of the realm will undermine this government’s already less than convincing claim to be a government for the whole of the United Kingdom.

Devolution, some people seem prone to forget, is not some new development. The establishment of a Scottish parliament in Edinburgh substituted legislative devolution for administrative devolution. If Unionism has a future now, it is one that depends on recognising that the United Kingdom is a land of anomalies and a patchwork of competencies. That is not something of which to be feared and, indeed, Conservatives have previously made much of the repatriation of responsibilities from Brussels that will pass to Edinburgh (and sometimes Cardiff and Belfast) as well as London. If that is considered both plausible and necessary, there is little substantive reason certain immigration opportunities could not be devolved too.

This creates an opportunity for Johnson’s government but only if it is large enough, and sufficiently imaginative, to grasp it. The answer to that question will reveal plenty about his ministry’s true character. This, then, is a test.