Are the European elections about to hand Ruth Davidson a major setback?

First things first - I've got an article in the Sunday National today about the voting system for the European elections.  You can read it HERE.  As you can see, one point I made at the end, which at the time of writing I thought was fairly uncontroversial, was that the Tories were likely to win two of the six Scottish seats, and that the SNP were likely to win either two or three.  I'm already going to have to downgrade my level of certainty on that prediction, because two fairly remarkable opinion polls appeared over the course of yesterday which suggest that all bets could be off.  This, for example, is YouGov's estimate of Britain-wide voting intentions for the Euro-elections...

European Parliament voting intentions (Britain-wide, YouGov):

Labour 24%
Conservatives 16%
Brexit Party 15%
UKIP 14%
Greens 8%
Liberal Democrats 8%
Change UK 7%
SNP / Plaid Cymru 6%

Scottish subsample: SNP 49%, Conservatives 12%, Labour 11%, Brexit Party 8%, Liberal Democrats 7%, UKIP 5%, Greens 3%, Change UK 3%

If that subsample were to be taken seriously, it would mean the SNP are on course to win an incredible four of the six seats, and Labour and the Tories are set to take one apiece.  Now, of course, it's only a subsample, and no individual subsample should be assumed to be reliable.  I'm particularly sceptical about the SNP's very high vote, especially bearing in mind that they've tended to underperform expectations in European elections over the last twenty years.  But what I think we do need to take seriously is the possibility that the Scottish Tories could fall well short of their performances in the local and Westminster elections of 2017, simply due to massive numbers of their pro-Brexit supporters switching to either UKIP or Nigel Farage's new party for one day only, just to send a message.  As the same trend can be seen in the Britain-wide numbers, there's no particular reason to think that the Scottish subsample is leading us astray about it.  I had assumed that the Scottish Tories might be more resistant to the Faragist menace than their colleagues south of the border, because that was the case five years ago, but it appears that things have changed.

The SNP, meanwhile, don't show any sign of leaking pro-Brexit votes, so this could be a perfect storm for Ruth Davidson - if the Tory vote share actually goes sharply down while the SNP gain in terms of both votes and seats, it would be a stunning reversal of the narrative of the last couple of years that the media have fallen head over heels in love with.  It could be the beginning of the end for the myth of Ruth and her magic powers.

It's hard to work out whether Farage's intervention in this race is counterproductive from his own point of view - the poll figures seem to suggest that all he's succeeded in doing is splitting the hardline Brexit vote, and preventing UKIP from emerging once again as the largest single party, thus squandering the chance of saying that the establishment have been punished for their "Brexit betrayal".  But it's possible that the lavish coverage he's been given by the broadcasters in recent days is just the start of a bandwagon effect that will help squeeze the UKIP vote and propel the Brexit Party into first place.

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UPDATE: Someone in the comments section queried the seats projection from the YouGov subsample and suggested that the SNP would need to be at nearly 65% to win a fourth seat.  That's categorically untrue.  As explained in the Sunday National piece, the D'Hondt formula is effectively slanted in favour of larger parties, which means the SNP would have a chance of winning four seats even on 40% of the vote.  At 65% they'd be more likely to win five seats, although that would depend on how the remainder of the vote is split between the other parties.

To demonstrate the point, here is how the D'Hondt calculation would play out for each individual seat if the YouGov subsample is right. 

First count: SNP 49, Conservatives 12, Labour 11, Brexit Party 8, Liberal Democrats 7, UKIP 5, Greens 3, Change UK 3

SNP win first seat

Second count: SNP 24.5 (49 ÷ 2), Conservatives 12, Labour 11, Brexit Party 8, Liberal Democrats 7, UKIP 5, Greens 3, Change UK 3

SNP win second seat

Third count: SNP 16.3 (49 ÷ 3), Conservatives 12, Labour 11, Brexit Party 8, Liberal Democrats 7, UKIP 5, Greens 3, Change UK 3

SNP win third seat

Fourth count: SNP 12.3 (49 ÷ 4), Conservatives 12, Labour 11, Brexit Party 8, Liberal Democrats 7, UKIP 5, Greens 3, Change UK 3

SNP win fourth seat

Fifth count: Conservatives 12, Labour 11, SNP 9.8 (49 ÷ 5), Brexit Party 8, Liberal Democrats 7, UKIP 5, Greens 3, Change UK 3

Conservatives win fifth seat

Sixth count: Labour 11, SNP 9.8 (49 ÷ 5), Brexit Party 8, Liberal Democrats 7, Conservatives 6 (12 ÷  2), UKIP 5, Greens 3, Change UK 3

Labour win sixth seat

Final tally: SNP 4 seats, Conservatives 1 seat, Labour 1 seat