What would a 'voluntary British union' actually look like?

The landmark has been closed for so long that even the paint on its shutters is greying, blistering, flaking off.

It is just shy of half a century since the Floral Hall was last used, since it became a place where history was almost made.

Back in March 1973 – at the height of the Troubles – the Art Deco ballroom with ringed with springy coils of barbwire, its perimeter patrolled by police and soldiers with German Shepherds.

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Why? Because this was where the votes were counted for Northern Ireland’s last border poll. Nearly 99% of ballots cast were for remaining in the UK. But only Unionists turned out. Nationalists stayed at home.

The referendum was a one-sided farce, with a chunk of the electorate questioning the legitimacy of the Northern Irish statelet, then itself barely 50 years old.

But the plebiscite marked a constitutional “year zero” for the UK.

That, at least, is the take of Scottish nationalist thinker Gordon Guthrie. How come? Because it established a principle of popular rather than parliamentary sovereignty.

The 1973 border poll was followed by a slew of other referendums on big ticket constitutional issues, like joining and leaving ‘Europe’, voting reform, devolution and independence.

Yet access to popular sovereignty – such as exercised in Scotland in 2014 – remains arbitrary, left to the whim of ministers in Westminster.

Outgoing First Minister Nicola Sturgeon – her planned indyref2 blocked – has called this a “democratic outrage”.

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Nationalists have started asking – mostly rhetorically – whether the constituent nations of the UK have a realistic right to self-determination.

But they rarely, if ever, talk about what a constitutionally voluntary union would actually look like.

Mr Guthrie thinks he has found a model for such a polity in the legislative wastepaper basket of 1970s Northern Irish politics.

The SNP member has drafted a whole new founding law for the British state, based on what he describes as a “lost masterpiece”, the never-quite-implemented Northern Ireland Constitution Act of 1973.

This legislation was designed to create a new devolved government in Belfast. It also stipulated that the people of Northern Ireland – not their elected representatives – must consent before the territory could join the Republic of Ireland.

Now that was a big deal. Such referendums, it said, could be carried out no more than once a decade. The GFA cut that interval to once every seven years. The old 1973 law got nowhere. But its core idea prevailed.

In Scotland we argue about the meaning of rhetorical warnings from Yes leaders that the 2014 indyref was a “once-in-a-generation” opportunity. But in fact we have no agreed constitutional or political framework for testing the voluntariness of our union.

So Mr Guthrie suggests a UK-wide Voluntary Union Act based on the Northern Ireland law of 1973. He admits it is funny that an independentista should be coming up with a plan to rethink the union state. But he has his logic.

“A good rule in politics is to always punch the bruise – the bruise here is... is the UK a voluntary union?” he said. “There is no direct Scottish Parliamentary constitutional electoral route to an agreed referendum – some mandates are more equal than others. The Supreme Court has ruled. We have run out of road.”

The SNP is currently trying to find a way out of this impasse. But it is not just nationalists who are “stuck”; unionists are too, and they show little appetite for coming up with an orderly and democratic way to manage the Scottish Question.

Mr Guthrie has proposed that his party does “what our opponents do not expect us to – to reach out, to make a grand offering with an open hand”. He continued: “An involuntary union is intolerable, a voluntary union is only what we sought when we asked for a Section 30 and a Supreme Court ruling.”

Some unionists – and especially British nationalists who reject the idea of the UK as a multi-national state – may see Mr Guthrie’s 1973 gambit as a trap, as an attempt by “separatists" to create a staging post for independence.

Those anxieties have merit. SNP activists like Mr Guthrie, after all, are not pretending they want to save Britain.

But nationalists – as Yes once again trails in the polls – are attempting to build a sustained majority. And that means capturing voters who may want Scots to have popular sovereignty but are not yet entirely sold on how it should be exercised.

The tricky bit for unionists is that they need these voters too. Which is why rethinking the nature of British state should be at the top of their agenda.

The 1973 Act – its full implementation kiboshed by unionists opposed to power sharing – was a response to a very different crisis to Scotland’s current dead end. Its context was violence and direct rule. We have peace and we have devolution.

Northern Ireland is one of just two places (that I can find) which enjoy a constitutionally stipulated right to democratic self-determination.

Its 1973 law was designed to enable a new autonomy in Northern Ireland, one based on the ill-fated Sunningdale Agreement on power-sharing. But unionists were not ready for this.

Direct rule was to go on for another quarter of a century until Northern Ireland got its Good Friday Agreement – or “Sunningdale for slow learners”, as former SDLP deputy leader Seamus Mallon once called it.

Scotland today is nothing like the Troubles in what TV reports in the Seventies still called “Ulster”. So some will see the old Northern Ireland Constitution Act, like Belfast’s boarded-up ballroom, as elegant but useless. But, with Scottish politics in flux, is it worth testing the idea of a Voluntary Union Constitution? I think so.