The crowds converging on London this weekend to march for a people’s vote will encompass many thousands of Scots because their country voted by a handsome 62% to remain in the European Union. Yet do a vox pop north of Hadrian’s Wall on a second referendum, and you’ll find most people assume you’re discussing what’s known as IndyRef2 – a rerun of the 2014 referendum on Scottish independence, which the unionist vote won by 55% to 45%.

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However, by the time Scotland’s first minister, Nicola Sturgeon, rose to address her party conference in Aberdeen this week, the polls were suggesting that 50% favoured Scotland seceding. Significantly, more people than not supposed Scotland would be wealthier in the EU and outside the UK.

The political landscape has changed because Holyrood and Westminster have diverged so strongly on policy. There is real fury in Scotland that the Home Office is still at large, stymieing the desire to secure the future of EU citizens, its existence obstructing a potentially liberal immigration policy.

There have been no attempts to marketise the health service in the country, unlike elsewhere in the UK, and a raft of social measures have passed that ensure no tuition fees, free personal care, and a childcare policy that gives every new child a baby box starter pack and, from next year, a £10 a week allowance.

It’s not a utopia. It’s not problem- or failure-free. But people increasingly know they want no part of a world in which a morally bankrupt Boris Johnson can become prime minister and Jacob Rees-Mogg leader of the House. They look in horror at the rise of Tommy Robinson’s English Defence League and of both Islamophobia and antisemitism.

Increasing numbers like the idea of living in a small, liberal, European nation state. That uptick in support in a raft of polls was not the only factor that produced two pledges from Sturgeon that on the surface leave her with little wriggle room among her more fervent pro-independence supporters. She has watched – although pointedly not participated in – pro-independence marches all over Scotland, with the most recent wave culminating in 200,000 turning up on her Edinburgh doorstep on a damp and dreich October afternoon.

Facebook Twitter Pinterest A Scottish independence march in Edinburgh on 5 October. Photograph: Duncan Bryceland/REX/Shutterstock

The fact that she has now pledged to ask for the powers to hold another referendum to be transferred to the Holyrood parliament by the end of this year – the section 30 order signed by both David Cameron and Alex Salmond in 2012 – and, crucially, promised her troops a new referendum in 2020, means that she placed herself on a collision course with the prime minister, and self-declared minister for the union.

For months she has been under pressure to be bolder. Her legendary caution has been founded on one central belief: that unless a referendum is run on the legally binding basis a section 30 order provides, what she calls “the gold standard”, she would be unable to persuade Brussels and the wider world of its legitimacy.

Backstage, however, much is going on to pave the way for a second vote. The referendums bill (Scotland) is nearing the end of its parliamentary journey. This says that when the power to hold one is devolved, it can proceed very quickly. It also waives the usual lengthy procedure to agree a question where one has been asked before. The very large elephant in this room is what happens when Boris Johnson – or any other premier – simply says no. In her speech, Sturgeon told other parties “not to even pick up the phone” if they didn’t accede to her demand.

Mike Russell, the minister responsible for constitutional matters including Brexit, hinted that his government might take the matter to the courts. Yet there is no guarantee this would work. A legal challenge to post-Brexit powers – even previously devolved ones – being repatriated to Westminster rather than Holyrood was lost in 2017.

It is a trope much used by commentators that Brexit has fuelled the desire for self-determination in Scotland. Moreover, that if there were to be a new vote for remain, the SNP’s fox would be shot. This is to misunderstand profoundly the current mood in Scotland.

Brexit is clearly a factor in a remain-voting country. It’s true, too, that there is enduring frustration at watching the DUP trotting in and out of Downing Street despite having 10 seats at Westminster, less than a third of the Nationalists’ 35-seat presence. Unlike the SNP, the DUP is also totally at odds with its own electorate. This frustration has been exacerbated by the Brexit ministers from Scotland and Wales being sidelined throughout the negotiations with Brussels, and the joint ministerial council reduced to little more than window dressing.

The Institute for Government has produced a report that says it would be unsustainable to deny a second independence referendum if Scots vote for parties supporting one. It says: “If the union is to survive, it must be because a majority of people in all four parts of the UK are persuaded that its survival is for the best, not because Westminster wields the power… to hold the nations… together against their will.”

Sturgeon insists the question is not what Scotland should do if Westminster says no to a referendum. The question, she says, is what gives anyone the right to refuse Scots the choice? These days it’s a question with resonance well beyond her party’s faithful.

• Ruth Wishart is a Scottish columnist and broadcaster