The Scottish subsample in the latest GB-wide YouGov poll is worthy of note, because it's the first time that I can remember for a very long time that the SNP have been above 50% in a YouGov subsample.
SNP 52%, Conservatives 19%, Liberal Democrats 11%, Labour 8%, Brexit Party 7%, Greens 3%
Of course it's extremely unlikely that the SNP are really on 52%. Assuming that YouGov still structure their Scottish subsamples correctly, the margin of error would be in the region of 8%, so the true vote share for the SNP could easily be something like 44% - a much more plausible figure. But nevertheless the SNP wouldn't be getting results like this, even as a freakish one-off, unless their vote was holding up exceptionally well. They'll take particular heart from the underwhelming showing for the Lib Dems and the disastrous showing for Labour. There's no scenario in which the wheels can truly come off for the SNP (by which I mean that they would do worse than 2017 and fail to take a majority of Scottish seats) without there being a pro-Labour swing. As things stand, it looks like Labour are going to have to make up huge ground over the course of the campaign just to get anywhere close to being back to where they were two years ago. Nothing is impossible, but it seems pretty unlikely that the SNP will be losing any seats to Labour this time. Meanwhile, the Lib Dems are polling lower in Scotland than in any other part of GB, in spite of having a shiny new Scottish leader.
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You may have seen the comments by Tory rebel Oliver Letwin suggesting that there is now a majority in the Commons for holding a second EU referendum before the general election, which he thinks could be delayed until next year. I'd suggest this should be taken with a pinch of salt, because we've heard confident claims many times in the past about the inevitability of a second referendum, but whenever it's been put to the test parliament has voted against the idea. One major obstacle is surely that the Labour leadership want any referendum to take place after the election.
But let's suppose for the sake of argument that Letwin is right and that a Referendum Bill is passed in this current parliament. What does Boris Johnson do then? He can't strike legislation down by decree, but by the same token it would be unthinkable for him to allow the 31st October deadline to pass and a second referendum to take place on his watch. That would be a humiliation that would surely finish him as leader of the Tory party. Which leads me to an inescapable conclusion: he would preempt matters by submitting his resignation as Prime Minister.
And then what? One of the stupid things about the Fixed Term Parliaments Act is that the resignation of a Prime Minister or government does not in itself set in train the 14-day deadline by which parliament will be dissolved unless an alternative government can win a confidence vote. A dissolution can only occur if MPs vote to bring it about by one of two specific mechanisms. If they choose not to do that, the current parliament continues and there has to be some sort of government. By convention, the Queen is supposed to appoint a Prime Minister who can command a majority in the Commons, but even if no such person exists, the Fixed Term Parliaments Act would effectively force her to appoint somebody anyway - she wouldn't be able to do the sensible thing and simply dissolve parliament with a view to finding a PM with a clear mandate. If the Tory leadership have vacated the pitch, and if the Labour leadership continue to show no interest in Jo Swinson's ideas for a compromise PM, the Queen would presumably have to appoint the available person who is closer than any other to enjoying the confidence of the Commons, and that person would be Jeremy Corbyn.
So that might well be the last-ditch plan to overturn any Referendum Act that is passed. Boris Johnson resigns, allows Jeremy Corbyn to become PM for a few days, and then seeks to bring him down by simple majority in a confidence vote - which would start the clock ticking for a general election under the Fixed Term Parliaments Act. The Tories would then stand on a platform of scrapping plans for a second referendum.