IT feels like a generation ago that Carles Puigdemont was forced into exile following his efforts to declare Catalonian independence.

The former president hit the news again last week by making a return to Barcelona to address independence supporters as a new Catalan government was sworn in.

“The right to self-determination belongs to the people”, he told those gathered. “Catalonia must be allowed to decide its future.”

And with that, he disappeared from right beneath the noses of the police officers under orders to arrest him.

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If his objective was to offer some morale-boosting theatre and to rile the “muscular unionists” of Spain, then it was mission accomplished. But for all that has happened since 2017, Catalonia remains firmly within the Spanish state with no obvious route to achieving independence.

Minus the interest of the judiciary, this might all sound a bit familiar to the ears of Scotland’s independence supporters. Whatever parallels can be drawn, though, Scotland and Catalonia are very different, both in historical claim and legal situation, as well as recent political history.

Nowhere is that more obvious than with the differences in the constitutional assumptions made by each central government.

Firstly, Spain has a written constitution – the UK does not. Also, the 1978 Spanish constitution refers to what its architects saw as the “indissoluble unity” of the Spanish state. Contrast this with the competing ideas of Scottish popular sovereignty versus English parliamentary sovereignty, and the fact that the UK state has no similar assertion of unity for itself written anywhere in law.

But just because the UK union exists on an assumption of consent, passive or otherwise, it doesn’t mean there’s any quick political wheeze that’s going to get Scotland out of it.

Regarding how we move on from here politically, I’m more concerned in grappling with the future than in contesting the past. However, what should be able to unite everyone is the principle that for Scotland to become independent, a means which can command both internal and external legitimacy is required.

And that can only happen when there is the unambiguous consent of a majority of Scottish voters for independence.

(Image: PA)

Here’s where it gets trickier. As much as it sticks in the craw to acknowledge, no matter how often we assert that the people of Scotland are sovereign, as the Catalan example shows, it cuts no ice with the rest of the world unless the process we follow is also recognised and accepted by the UK Government.

So the key question needing answered is surely this: if the UK union is based on consent, how then can that consent be withdrawn?

It is a question that gets to the heart of the democratic principle of the right of Scotland to self-determination.

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Crucially, it is a question that the leadership of the Unionist parties will fail to answer at their longer-term electoral peril.

The good news is that we are not the only people on these islands asking that question. Just as Brexit reanimated the independence question after what looked like a generational setback in 2014, it has also given a new dimension to the question of Northern Ireland’s place in the Union, and how it too might leave the UK if a majority emerges which wishes to do so.

As someone from County Antrim who has long called Aberdeenshire home, I need no reminding of the many differences between Scotland and Northern Ireland. However, there are parts of the Good Friday Agreement relating to Northern Ireland’s political status which make very interesting reading in a Scottish context too.

Firstly, the agreement recognises that it is for the people of Ireland alone to exercise their right of self-determination on the basis of consent.

Secondly, it commits the Secretary of State to organise a referendum if at any time it appears likely to them that a majority of those voting in Northern Ireland would express a wish that it should cease to be part of the United Kingdom.

It then goes on to clarify that any such vote would be decided on a simple majority, and that if any such poll is held, there need only be an interval of seven years before another can be held. In other words, the same amount of time that has elapsed since Mr Puigdemont last addressed a crowd in person in Catalonia!

I believe Holyrood should have the power to hold a future vote on independence whether a Westminster government agrees with doing so or not. But I’m not too fussy about the means of getting that vote – it’s far more important that we get it, and that when we do, we manage to persuade a majority to give us their support this time round.

Challenging the Westminster parties to concede the principle of consent in letting Scotland determine its own democratic future points the way. But as in Northern Ireland, it is a principle which will only have useful effect when we also have sufficient numbers consistently backing a change to the status quo.

Just like their having continued unfettered access to the EU single market, if being free to choose your own future is good enough for folk in Northern Ireland, it’s good enough for folk in Scotland too.