The National:

THE new Britain-wide poll from Opinium is a landmark in that it shows Labour ahead of the Tories for the first time since the 2019 General Election.

But perhaps of greater interest from a Scottish perspective is that it also shows the SNP ahead of the Liberal Democrats (by 6% to 5%) across the UK, which is quite an achievement when you consider that fewer than 10% of the poll's respondents are even eligible to be SNP voters.

This isn't a bolt from the blue, though - most recent polls have failed to show much clear water between the LibDems and the SNP, and there have been quite a few occasions when the two parties have been tied.

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Of course, it would be bogus to present this as a proper horse-race, because the vast bulk of voters the LibDems have lost since their glory days are not in Scotland and have thus not gone to the SNP. But there is perhaps some concrete significance if the LibDems cease to be the undisputed third party across the UK in terms of popular vote, and if their challenger is the SNP rather than another London party.

Despite the SNP's status as the third party in the Commons since May 2015, the broadcasters have failed to abandon the paradigm of "the three major parties", which includes the LibDems but not the SNP. The popular vote has been one of the excuses for this. But if the SNP were firmly in third place in terms of both seats and votes, the excuses would start to run out.

Is it realistic to think that polls such as this will keep on coming? Possibly not.

The Opinium numbers may well have been caused by a statistical quirk, with the LibDems' vote at the lower end of the margin of error and the SNP at the higher end.

If the squeeze on the LibDems continues to the point where they appear to be a total irrelevance, it's not completely inconceivable that the SNP could build up a sustained polling advantage

Much depends on how Sir Ed Davey fares as LibDem leader, because it's next to impossible for the SNP to poll higher than around 6% in UK polls. If they were to consistently stay in third place, it would require the Lib Dems to slip to 5% or below, and more likely 3% or 4%.

Things don't look that grim for Davey yet, although he must be bitterly disappointed not to have secured any bounce after being confirmed as full-time leader.

At the moment, moderate voters seem to be coalescing behind Sir Keir Starmer in England and Nicola Sturgeon in Scotland. If the squeeze on the LibDems continues to the point where they appear to be a total irrelevance, it's not completely inconceivable that the SNP could build up a sustained polling advantage over them.

Naturally the other side of the equation is that the SNP would have to maintain a good level of support, although that bit is somewhat easier, because roughly 10% of lost vote share in Scotland translates into only 1% in Britain-wide polls.

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Nevertheless, in the overall scheme of things it's not that long ago that the SNP were struggling to hold on to a slender lead in Scotland after the setback of the 2017 General Election, which meant that they were typically polling at only around 3% across the UK.

The fact that 6% is now even possible is testament to Nicola Sturgeon's total dominance of the current political scene in Scotland. Ironically, part of the reason that's happened is that the televised briefings on the pandemic have allowed her to overcome the aforementioned problem of the broadcasters failing to treat the SNP with the prominence they warrant as the UK's third party.

It's little wonder, then, that the Unionist parties, including the LibDems, have been so hellbent on persuading the BBC to either drop the briefings or to give punditry slots to other politicians.