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It seems clear that he said it because it is what he believes. Why should Northern Ireland have a mechanism set out in law by which they can leave the United Kingdom, but not Scotland?
That is fair enough. It is a perfectly reasonable position.
But this is Westminster we’re talking about, and in one unguarded moment, the Prime Minister just undid more than a decade’s work for the Unionist parties.
Time and time again, SNP MPs have been told the same message, loud and clear by Tory and Labour ministers: “Now is not the time.”
Now Burnham is saying: “Here’s when it will be time.”
If it was a gaffe, it was one of the most spectacular gaffes I’ve seen on the Commons floor – and I saw Nadine Dorries in her prime. But if it was a genuine signal of a change in approach from the UK Government, it is a momentous shift and independence campaigners are right to jump on it.
It is worth dwelling on precisely what the Prime Minister said.
Asked by the SNP’s Chris Law about the possibility of putting on statute the grounds for indyref2, analogous to the situation for Northern Ireland, Burnham said: “He mentions the Good Friday Agreement, and I will stick to it 100%.
“And I would also remind him on that question of a border poll, it is to be considered by the Northern Ireland Secretary when there is a clear consensus in the country, when public opinion has changed to the point where the call has to be considered.
“I would say exactly the same situation in Scotland.”
From this, we are to understand that the PM’s position is that if it is judged – presumably by the Scottish Secretary – that there is “clear consensus” for independence, there should be a referendum.
That is pretty clear. Almost immediately, Burnham’s spin doctor tried to muddy the waters, pointing journalists in the lobby briefing after PMQs to Labour’s opposition to independence and another referendum, as set out in the 2024 manifesto.
But there was a problem for the Prime Minister’s aides: that wasn’t what he said at the despatch box. He’d set out a route to securing indyref2 which, however vague and however arbitrary, still represented a major shift in the UK Government’s position.
If this is the new position, it moves Labour into territory that some in the SNP – and outside the party, notably Kezia Dugdale and Stephen Noon’s report for Glasgow University in 2024 – have occupied for some time now.
It is important also not to get ahead of ourselves. While some independence supporters want a Northern Ireland-style “mechanism” for indyref2, the Good Friday Agreement framework still vests an enormous amount of power in the Secretary of State, who gets the say on whether a vote is called.
And Burnham’s comments have the added benefit, for him, of putting the ball in the SNP’s court. Of the last 10 polls on this question, Yes has been in the lead in eight, though almost always short of an outright majority when "don't knows" are included.
Their task and that of the wider independence movement will be to build support to a level that the UK Government cannot deny.