Some in the SNP may welcome Sunak stepping in on gender - Euan McColm

The slightest suggestion the United Kingdom government might intervene to block an act of the Scottish Parliament should, you might think, be more than enough to unite all nationalists in righteous fury.

After rejecting First Minister Nicola Sturgeon’s demand for a second independence referendum, evil old Westminster would surely give the separatist campaign quite the boost if it were to start throwing its weight around on the matter of what laws MSPs are entitled to pass.

But we live in strange times. Right now, there are SNP members and - whisper it - elected members who wish to see just such an intervention take place.

Days before Christmas, MSPs voted in favour of making it easier for people to legally change their gender.

The gender bill has been the Scottish Parliament's most controversial piece of legislation

But while supporters of reform of the Gender Recognition Act hailed the move as a win for progressive politics, a majority of Scots are opposed to it. A YouGov poll, published before MSPs voted, show almost two thirds believe the new legislation is wrong.

The matter has caused division within the SNP. Leading MP Joanna Cherry has criticised it for impacting on women-only spaces, while Scottish government minister, Ash Regan, quit her post after declaring herself unable to support a change in the law. There are others within Scotland’s ruling party who share that view.

And so the issue of whether Prime Minister Rishi Sunak might direct Scottish Secretary Alister Jack to intervene is not so politically straightforward as it might seem. Certainly, First Minister Nicola Sturgeon would characterise such a move as a profound attack on democracy but it might also further expose SNP splits on the subject.

Why is the UK Government taking an interest? The truth is rather more mundane than some would like it to be.

While members of Scotland’s SNP-Green government paint this as evidence of Westminster’s contempt for Holyrood - or “Scotland” in the nationalist argot - the interest of ministers in Whitehall has been triggered by concerns that the reforms passed at Holyrood may have a negative impact on UK-wide equality legislation.

In the next few days, Sunak and Jack will make a final decision on whether to invoke section 35 of the Scotland Act. Such a step would prevent Holyrood’s presiding officer from submitting the new bill for royal assent.

The Scottish Government remains adamant that its decision to cut the waiting time for a gender recognition certificate and remove the need for a diagnosis of gender dysphoria in favour of a system of self-identification will have no impact on England and Wales but concerns have been raised about a new system that would see people who change gender in Scotland having a different legal sex when they cross the border.

During a visit to Scotland, which included private talks with the First Minister, Rishi Sunak expressed concern about the impact of the bill across the UK, promising to set out next steps this week.

Of course, regardless of how he presents this dilemma, the PM faces a decision based not only on the legal position but on the politics. There are some within the Conservative Party who believe it would be wrong to intervene purely on the basis that to do so would provide ammunition to Scottish nationalists.

But other Tories are less inclined to let this piece of Holyrood legislation proceed. The former advocate-general for Scotland, Lord Keen of Elie, last week wrote that Westminster could not allow the Holyrood bill to gain royal assent because of its impact on the rest of the UK. According to Keen, it would be “constitutionally improper” for the UK government to permit a devolved administration to enact a law that would have “a material impact upon the operation of the law throughout the United Kingdom”.

Even if the UK government decides this is not the fight it wishes to pick with Nicola Sturgeon, the passage of the bill into law is not yet guaranteed. It is expected that the legislation, should it make it into statute, will face legal challenges from feminist campaigners who believe it erodes the right to same sex spaces.

Interestingly, I have found that some in favour of reform of the gender recognition act believe such a challenge might succeed.

“I support the change in the law,” one SNP activist told me, “But there’s been a lot of ‘this is all fine’ from the First Minister and not a lot of substantial engagement with the arguments of people who’re against it. I hope that if anyone decides to take this to law, they lose but I can’t say, hand on heart, that they will. We wouldn’t have the Prime Minister threatening to step in if this was all legally watertight, would we?”

Without question, reform of the gender recognition act has been the most controversial piece of legislation passed by MSPs since the establishment of the Scottish parliament in 1999. For ministers, it is more than merely a change in the law, it is deeply symbolic. In their view, it shows Scotland as the most tolerant and progressive part of the UK. And with young people more likely to support reform, it does no harm in encouraging a new generation to back the independence project.

However, wider public opinion is not currently with Nicola Sturgeon. Voters across the political spectrum share concern that reform of the gender recognition act will impact on women’s rights.

If Rishi Sunak decides, in the days to come, that this law cannot be allowed to pass, many nationalists will say he has overstepped the mark and helped make the case for why Scotland must go it alone.

Others within the SNP will, however, be perfectly happy to see a Conservative Prime Minister scupper an act of the Scottish Parliament.

Strange times, indeed.