Scottish independence: Nicola Sturgeon's 'de facto' referendum plan is going down badly on the doorsteps – Alex Cole-Hamilton

There is an urban legend in UK politics that when the BBC’s national exit poll was published at 10pm on the night of the 2017 General Election, Theresa May left the room to be sick.

Theresa May's disastrous decision to call a general election in 2017 has a lesson for Nicola Sturgeon (Picture: Justin Tallis/WPA Pool/Getty Images)

She had taken a seemingly unassailable poll lead over Labour and thrown it away, along with her parliamentary majority.

Earlier in the campaign, with victory all but assured she had decided that she could expend some of her political capital and her poll lead, by having, what in her mind, was a grown-up conversation with the British public about how we should pay for social care. That involved the sale of family homes to pay for care home places and so the ‘Dementia Tax’ was born. It turned out to be political strychnine. It made her, for the briefest of moments, the least popular Conservative party leader in history.

The lesson of this story is clear, politicians don’t get to tell the electorate what an election is about, they tell us. Elections give the people their say on what matters to them and they give us our instructions. It is clearly a lesson that Nicola Sturgeon has failed to learn. The ink wasn’t even dry on the Supreme Court judgement bluntly stating with surprising clarity that the Scottish Parliament did not have the power to hold another referendum on Scottish independence before the First Minister pivoted to her Plan C.

She appeared at the Apex hotel on a podium festooned in the acid yellow of the SNP to declare that the next general election will take the place of a referendum and that her party would regard victory in that election as a mandate to begin the process of removing Scotland from the UK. Before close of play the Greens had agreed and will also fight that election on the proposition that “if you vote for us, Scotland will become independent”.

I find that unspeakably arrogant. The next general election will be about many crucially important matters from the cost-of-living emergency to the the climate crisis and the state of the health service. Yet the SNP and the Greens are effectively saying “yeah, yeah, forget all that – this is only about our thing”. Such an approach should exclude both the SNP and the Greens from answering any questions in TV debates beyond those relating to the constitution, because by their logic, on those things they’ll have literally nothing to say.

The wheels are already coming off the clown car. According to our canvas teams out knocking doors over the weekend, the so-called ‘de-facto’ referendum is going down like a cup of cold sick with the voters. Added to this, several prominent nationalist MPs (clearly worried about their seats) broke ranks over the weekend to state that they didn’t think this had been thought through.

The Scottish Liberal Democrats won’t play this game. We know how important these elections are. If the SNP and the Greens won’t fight this on the cost of living or the climate emergency or the health crisis, we will.

Mark my words, the voters will punish Nicola Sturgeon for trying to make the election about her pet project. Theresa May could tell her that.

Alex Cole-Hamilton is Scottish Liberal Democrat MSP for Edinburgh Western