Whilst it is definitely Scotland’s decision on whether or not to leave the union, it is legally and constitutionally not their choice whether to have another referendum on it. How they get there is difficult to see, but it is worth them trying.

In the General Election, the Scottish National Party achieved 48 seats out of the 59 available with 45% of the vote. This was on a manifesto in which they clearly stated they would seek a second independence referendum.

45% is a resonant result. That was the result in 2014 when the first Scottish Independence referendum happened. With 84% turnout, the SNP cannot blame political disengagement for that result. 55-45 is a pretty clear majority in a referendum. But it is not in the nature of the SNP to give up.

They point to the 2016 Scottish Assembly elections, in which they got 46% of the constituency vote but not quite a majority due to how the AMS electoral system worked. In their manifesto it said that there would be another referendum if certain events happened, including Scotland being taken out of the EU against its will.

That happened in 2016, and every single Scottish region voted to Remain. But Theresa May refused to grant a referendum and she didn’t even have a majority for much of her reign. Why would Boris Johnson allow one with a majority of 80?

He could justifiably argue that London also voted for Remain in 2016, so why should Scotland get a second independence referendum without London getting a first? It might be better for Johnson instead to give additional devolved powers to Scotland, give it more protection against Westminster legislating on devolved areas, or even involving Scotland in some of the international negotiations.

The stakes are high though. The transition period ends in December 2020 so if Scotland leave the UK by then they can theoretically stay in the EU.

But let’s say somehow Johnson gives them that chance, the rest of the EU would have to approve what is effectively a new country joining the EU, and Spain can’t do that as it would just encourage Catalonia to try to do the same thing. That’s without the fiscal imbalances the Scots would be left with after leaving, which in theory would preclude them from being able to join the EU independently. It remains to be seen whether their idea that they wouldn’t have to rejoin as they had never left would be allowed.

Talking of Catalonia, they went down the path of holding an illegal referendum on independence, which is an option for Scotland, although the result would be illegitimate. Johnson has no reason to grant them a referendum as their votes are no longer important to him. The SNP are considering legal options as well as political options and it is simply not clear what they can do to achieve a referendum.

It’s also not clear they would win a second referendum even if they did get one. The idea in 2014 was that, because Scotland would remain in the EU with the rest of the UK, trading conditions wouldn’t have to change. But if the rest of the UK has left then somehow Nicola Sturgeon has to answer questions about how Scotland makes money with what would have to be a hard border between it and the UK. One would assume there would be a Common Travel Area for movement of people, like with Ireland, but if trading conditions worsen for Scotland that movement might be one way.

IF he did offer a referendum, Boris Johnson could also offer a ‘Devo Max’ option in addition to the Yes and No options, which would attract waverers. This might not be fair, but the point is that the UK Government has control of the entire process.

Learning from the 2016 EU referendum, and actually from the 2014 Scottish Referendum, which is regarded as a benchmark for referendum organisation in many ways, another referendum shouldn’t be rushed. It could be argued that it would be better to wait until the UK has properly left the EU, so the choice is clear between the alternative constitutional futures. The UK government could also suggest that the Scottish Assembly election is fought along the lines of whether there should be another referendum, with a threshold perhaps for the vote share needed for it to happen.

Yet I feel some sympathy for Scotland. Boris Johnson chose to name constituencies he had won and didn’t name a single one from Scotland. In fact he didn’t mention Scotland. I am not entirely sure he has any plans to travel there.

The case for self-government for the Scots is increasing, but the constitutional case for them getting there is far less clear.