My concern for the SNP over the last couple of weeks has been the risk they might slip to second place in Westminster voting intentions - not behind the Tories, who have probably come pretty close to hitting their natural ceiling of support in Scotland, but behind Labour, who now have considerable momentum behind them.
There have only been a tiny handful of voting intention polls since the general election - probably because most polling firms called the election wrong, and there's little point in commissioning a poll from those that did until they've reviewed their methodology. However, that hasn't applied to Survation, who famously got the election right (in defiance of Andrew Neil's clueless sneering in this extraordinary clip which has been charitably described as his "Michael Fish moment"). The Scottish subsamples of the two post-election Survation polls show a contradictory picture - the online poll had the SNP still in the lead with Labour in second place, but the phone poll had Labour ahead with the SNP in second. The good news is that the phone subsample seemed to be very obviously skewed - Labour also had a significant lead on how people in Scotland recalled voting in the general election, when they should actually have been in third place on that measure. So as of yet there's no convincing evidence from Survation that Labour have edged ahead of the SNP.
On Saturday night, word came through of an enormous GB-wide Panelbase poll which had Labour on 46% and the Tories on 41%. A combined total of 87% for those two parties is unusually high, giving rise to the obvious concern that the SNP were being squeezed out in Scotland. However, now the datasets have been released, it appears that isn't the case at all. Irritatingly, there are no Scottish subsample figures, but there's enough information to make some educated guesswork. The most important fact is that, unlike the Liberal Democrats, the SNP have retained the support of well over 90% of the people who voted for them earlier this month. As you'd expect, the small minority of votes they've lost have essentially gone as a bloc to Labour, but that direct swing would be nowhere near enough on its own to push Labour into the lead. Some of the SNP losses have been offset by new support from elsewhere, and a very rough calculation suggests that the SNP's share of the vote has probably only slipped from 37% to something in the region of 35% or 36%. An extra 2% for Labour wouldn't even take them to 30%, so unless there has been very substantial movement from the Tories to Labour, it's hard to see how the SNP can possibly have been overtaken in this poll's Scottish subsample (which, it must be stressed, is an unusually large subsample of several hundred people).
After the relentless 'shock and awe' media propaganda campaign of the last couple of weeks which has attempted to finish off both the SNP and the Yes movement for good, I'd suggest it's hugely heartening if the SNP still have some sort of lead in Westminster voting intentions, even if that lead is fairly modest.
[Update : Either Panelbase have updated their datasets over the last couple of hours or I somehow missed the relevant part earlier, but the Scottish subsample is now available. The figures are pretty close to the assumptions I made above : SNP 34%, Conservatives 30%, Labour 29%, Liberal Democrats 5%, Greens 1%.]
Bear in mind that the favourable wind behind Jeremy Corbyn isn't going to last forever, and Scottish Labour's chances of seizing the moment have been dealt a severe blow today by the nauseating Tory-DUP agreement, which on the face of it leaves Theresa May in a fairly healthy arithmetical position in parliament...
Conservatives + DUP : 328
All other parties (excluding Sinn Féin) : 315
That's a majority of 13, which means that it would take 7 by-election defeats or defections to put the government in an untenable position. By-elections have become rarer in recent years, perhaps simply because general life expectancy has risen. There were only three by-elections in Conservative-held seats in the entire 2015-17 parliament, and all three were caused by resignations rather than by deaths. I'd suggest that at the very least it would take three years to wipe out the Tory/DUP majority, unless there is a sudden spate of defections from the Tories to either UKIP or the Lib Dems (or both).
On the other hand, the current situation has revived the old concept of a 'working majority', meaning a few seats over and above the total required for an overall majority. Unless relations between the Tories and the Lib Dems warm up considerably, there is no real 'buffer' for the government outwith their own ranks and the DUP ranks. The only opposition MP that would probably vote for them on a confidence vote is the independent Northern Ireland unionist Lady Hermon, on the basis that she wouldn't be able to accept Jeremy Corbyn as Prime Minister (although even she has very well-known anti-Tory leanings). If the government lost as few as four or five by-elections, they would arguably have lost their 'working majority' because they wouldn't be able to get their business through the House reliably, and a general election would perhaps become inevitable at that point. But even that would take quite a while.
So, for better or worse, it looks like the SNP will have plenty of time to steady the ship before facing the electorate again - which is another good reason why they shouldn't panic and needlessly reverse their policy on an independence referendum.