WHERE does power lie?

This is the question at the nub of Nicola Sturgeon’s decision to up the ante in the intriguing constitutional poker game between Edinburgh and London by planning for a home-made referendum.

Last week, Ian Blackford, the SNP’s leader at Westminster, in an interview with The Herald highlighted a quote from the 1953 court case, McCormick versus the Crown, which was, that “parliamentary sovereignty is a purely English concept and has no part in Scottish constitutional history”.

In recent years, the SNP has repeatedly referred to the Claim of Right, the principle of which goes all the way back to the time of Robert the Bruce and the Declaration of Arbroath in 1320; that is, that it is the Scottish people who are sovereign not parliaments or kings.

Indeed, in the last Westminster parliamentary session MPs debated the issue with the Conservatives supporting a motion on it, basing this on how the “significant deepening of devolution” through Scotland Acts had supported the Claim.

It was also pointed out, much to Nationalist annoyance, that the Claim had been firmly put into practice by the 2014 independence referendum when the nation made its feelings known about Scotland staying within the Union. And, indeed, Boris Johnson has insisted, on the basis of that, it is he who is the “voice for the majority of Scots” and not the First Minister.

There has been much constitutional chatter of late over what the SNP could do if the Prime Minister just kept saying no to facilitating Indyref2 even if it secured a majority in May’s Holyrood elections.

Joanna Cherry, the legal eagle who is the party’s home affairs spokeswoman, suggested going the Ireland route - but without, of course, the violence that ensued in the 1920s - ie, win a majority of seats at an election, declare a provisional government of an independent Scotland and begin negotiations with London.

It was only last autumn that Ms Sturgeon insisted the SNP did not need a Plan B on securing Indyref2 but internal party pressure seems to have engendered a change of approach; that if Westminster does not facilitate a second vote on Scotland’s future, Holyrood will press ahead unilaterally to hold its own, challenging the UK Government to test the extent of its powers in the courts. Which, of course, it would do.

Some have described this as the Catalan option. But there will likely be one very big difference. The Catalans held their referendum in October 2017, weeks after the constitutional court of Spain ruled it would be unlawful. The chances are if the UK Supreme Court ruled against Edinburgh, the First Minister and her colleagues would not risk what the Catalan separatists did: arrest; jail and exile.

One key political imperative behind the move by the SNP leadership is to keep the issue of Scottish independence front and centre of the UK’s political agenda, helped by the Sunday Times polls, which not only suggested Scotland wanted a vote within five years on its future within the Union but so too did Northern Ireland.

Last week, George Osborne, the former Chancellor, admitted that Brexit, given the position Northern Ireland had been placed in on trade with one foot still in the EU, meant the future of the Union was the “central political issue of the coming decade”.

One important caveat to the SNP leadership’s plan is that its Indyref2 would have to wait until the pandemic is behind us, which, of course, at present is an unknowable timescale; despite Mr Blackford’s assertion that a second referendum remains possible this year, the odds seem highly against this.

Ms Sturgeon made clear she had no plans to delay the May poll even if it had to be undertaken completely by a postal ballot. Given there have now been 20 consecutive opinion polls placing the Yes cause ahead, it is understandable that, politically, she does not want to lose moment and let slip the window of opportunity now afforded the SNP to press hard for another crack at an independence vote.

From the Downing St bunker, while still overwhelmingly focused on battling the Covid monster, there is more talk about “what to do about Scotland”. Michael Gove, the PM’s point-man on the Union, held talks with senior ministers last week to map out a strategy to save it.

Expect in the coming weeks a lot more talking-up the 314-year-old relationship, a beefing up of No 10’s Union Unit, more ministerial visits and a keynote speech from the Minister for the Union himself.

Mr Osborne’s advice to Mr Johnson was if he wanted to avoid the ignominy of losing the Union, then there was a simple answer: avoid having a vote on it; advice I seem to remember he gave David Cameron in the early 2010s.

Legal experts have already argued that parliamentary legislation is clear that, by law, constitutional matters like the granting of referendums, are reserved to Westminster.

While the Scottish Government’s lawyers might argue about the natural democratic justice of the Claim of Right or as John Swinney said on Sunday the “wisdom of the argument,” chances are the Supreme Court judges will look at the issue strictly on the grounds of law and so rule in Westminster’s favour.

But one option suggested if this were to happen is that the SNP leadership could seek to hold an advisory poll on beginning negotiations with London about a full-blown referendum. Again, the point of this would simply be to keep the political pressure on Downing St and maintain the media focus on Scotland and the arguments for independence.

Such a process could all take many months, possibly years, with the political ding-dong of Scottish independence resulting in saturation coverage across the press, TV, radio and social media. Constitution-fatigue might begin to set in.

Yet as the song goes when an irresistible force meets an immovable object, something’s gotta give. The question will be: what?