If they think they could win it, they could hold their own "people's poll" which would not be regarded as legally or constitutionally binding on Westminster and be derided as a glorified opinion poll. Assuming their supporters are more likely to turn out for a non-binding poll, a win could put added pressure on Westminster to concede a form referendum, something the Tories won't allow, but Labour might, specially if they needed SNP support to form a government post the next election.

At the moment everything Boris does is a gift for the SNP, because none of it takes account of Scottish sensibilities and is so obviously English ruling class inspired. If the SNP can't win even an indicative poll now, they never will.

Index of Frank's Diaries