Back in September, Scotland’s First Minister Nicola Sturgeon mobilised her troops. Standing on the stage at the party's conference, watched by thousands of SNP supporters, she instructed activists to speak to at least five people each month in the run-up to St Andrew’s Day.

At the time, with opinion polls against independence and the possibility of a soft Brexit still dangling above the Remainer heads, it seemed like a diversion tactic.

But by March, staying in the single market had been ruled out. Support for Scottish independence rose to 50 per cent, according to an Ipsos Mori poll. And Sturgeon has now declared that she wants another vote by 2018.

Which will leave a lot of Scots asking: “Where’s the unionist campaign?”

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Now that Alistair Darling, the former Labour Chancellor, has retired from frontline politics, there is little doubt about who the star of Scottish unionism is. Ruth Davidson, the lesbian kickboxer who single-handedly revived the Scottish Conservatives, did so by defining her party as the voice of the union.

In the 2016 Scottish Parliament election campaign, held before the Brexit vote, the Scottish Tory party leader pledged to do “a specific job” – oppose a second indyref.

However, despite Davidson self-described reputation as a “photo tart”, she is unlikely to spearhead a campaign. The Scottish Tories’ official position on a second referendum is denial (to acknowledge it is seen as playing into the SNP’s hands). She is also seen as too divisive for a cross-party campaign.

“I think Ruth is a very talented politician and a good communicator,” Blair McDougall, who was head strategist on the 2014 cross-party Better Together campaign, tells me. “But she is not a figure everyone would unite around.

“I think she is smart enough to know a Scottish referendum isn’t the next stage in the rehabilitation of the Scottish Conservatives.”

If a second referendum should be called, McDougall expects unionist politicians to accept less prominence than in 2014.

“You need politicians to do the dog-fighting in the TV studios when there is a particularly hot debate,” he says. “But actually this time it is probably more fruitful to be a campaign that is led by civilians.”

While many of Better Together's big beasts are savouring retirement, the prospect of a second referendum is already causing some of them to stir.

Former Prime Minister Gordon Brown’s last-ditch speech in favour of the union has been watched more than half a million times. Since the EU referendum – in which he made an equally impassioned, but less successful pro-union intervention – Brown has been lobbying for a federalist solution to the UK’s constitutional woes.

McDougall describes Brown as “indefatigable”, but expects him to focus his attentions on the “Labour side of things”.

This touches on another change from 2014. Labour entered the Scottish referendum as a party defeated in Westminster, but still holding 41 of Scotland’s 59 seats. Today, only one Labour MP, Ian Murray, remains. Since the referendum, activists have fought and lost two elections and an EU referendum. They are exhausted and demoralised.

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Then there are the issues. In 2014, the Better Together campaign’s message of cold, hard economic facts worked. Scots voted 55 per cent to 45 per cent to remain in the UK.

McDougall believes economic realism is still the best strategy, if focused on an argument about protecting the NHS, and other public services put at risk by an economic crisis.

Scots on both sides of the 2014 debate have remarked to me that, as the Brexit negotiations sour, voters may think twice about quitting another economic union.

Others are less convinced. The veteran campaigner I speak to compares the Better Together campaign to the later Remain campaign, which backfired after being parodied as “Project Fear”.

He says of the 2014 message: “It got us to the finishing line, but it didn’t make people feel particularly good.”

Some of the unionists I speak to believe a second pro-union campaign would be more targeted, with different messages for “left behinds” who voted to leave the UK, but approve of Brexit, compared to the pro-Remain pro-EU crowd in leafy Edinburgh neighbourhoods.

Nevertheless, unionists fear the SNP may summon an emotional nationalism powerful enough to eclipse spreadsheet slogans – and that Westminster may inadvertently help if MPs try to block a second poll.

“Most people I’ve spoken to think Sturgeon wants to have a fight about getting to hold the referendum,” the unionist campaigner tells me. “The moment [Westminster] Parliament turns them down, they’ve got a grievance.”

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For now, the Holyrood and Westminster gossip is focused purely on whether there is going to be another referendum, and if so, when. But to me, the lack of an organised union movement betrays a deeper challenge for the UK constitution.

In 2014, Brown declared that Scottish achievements happen “not in spite of the union but because of the union – and none of us is any less a Scot as a result of it”.

It was still possible, at that time, to imagine a Lib-Lab coalition taking power in Westminster the following year. The UK’s membership of the EU was intact. The economy was improving.

Since then, Scottish Tories aside, the unionists have lost representation in Westminster, lost membership of the EU, and spend their energy fighting cuts and debating the impact of Brexit on the economy.

Even if a second referendum is never called, progressive unionists have been left homeless by the UK’s mainstream parties. The Tories ask them to defend the UK's single market while turning their back on the EU’s. Labour, from opposition, is asking the same. Neither party is making the case for a soft Brexit, let alone a coherent argument for the ideal of unionism. If it dies in Scotland, perhaps not in 2017, but in 2020, or 2025, they will only have themselves to blame.