As expected, the Shetland by-election proved to be just too big a mountain for the SNP to climb, but by any normal standards the swing in their favour was enormous.
Shetland parliamentary by-election result (29th August 2019):
Liberal Democrats 47.9% (-19.5)
SNP 32.3% (+9.3)
Independent - Thomson 10.9% (n/a)
Conservatives 3.7% (-0.1)
Greens 1.6% (n/a)
Labour 1.3% (-4.6)
Independent - Stout 1.1% (n/a)
Independent - Scott 0.6% (n/a)
UKIP 0.5% (n/a)
Independent - Tait 0.3% (n/a)
That's a swing of more than 14% from the Liberal Democrats to the SNP. If that had been the result of a by-election on the mainland, it would look like an unmitigated disaster for the Lib Dems and their new leader Jo Swinson, because if national polls are to be believed they should be closing the gap in seats they don't hold, and sailing out of sight in seats they do hold. They certainly shouldn't be seeing their vote slump in a previously rock-solid heartland. However, we've known since the European election in May that the Northern Isles were bucking the national trend for whatever reason, and we've always known that localised trends in island constituencies don't usually have any wider significance, so the Lib Dems will probably just feel relieved to get out of this with a win of some description. The SNP will also be pleased, though, at this demonstration that there aren't any no go areas for them in Scotland.
There have been some suggestions that the SNP's biggest failing in this campaign was in the realm of expectation management, ie. that they allowed the impression to take root that they might actually win Shetland outright, which now leaves the big swing in their favour looking like a disappointing result. But I think sometimes you have to build a sense of excitement about a campaign if you want a decent outcome. There's not going to be much of a bandwagon effect if people think your aim is a distant second place.
Oh, and it shouldn't go unmentioned that the Tories specifically said in their election leaflets that if voters wanted Brexit, their only option was to vote Tory. So presumably this result means that 96.3% of Shetlanders don't want Brexit?
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There was also a substantial swing to the SNP in a local council by-election in East Kilbride...
East Kilbride Central North by-election result (29th August 2019):
SNP 46.5% (+4.2)
Labour 20.3% (-11.3)
Conservatives 14.6% (-4.1)
Liberal Democrats 12.4% (+9.9)
Greens 4.5% (+0.6)
UKIP 1.4% (n/a)
Scottish Libertarians 0.4% (n/a)
It's worth bearing in mind that the above percentage changes are from the baseline of the 2017 local elections, when the SNP's national vote stood at 32%. So the SNP are not necessarily setting the heather alight with a 4% increase. But what really matters here is the catastrophic drop in the Labour vote - if that trend continues, the SNP will sweep the board wherever Labour are their main opponents in any snap Westminster election. There still appears to be every chance that Scottish Labour will once again by reduced to just one seat (Edinburgh South).
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How can you tell the difference between a Westminster by-election and a local council by-election? The declaration of a Westminster by-election result is pretty much always broadcast live by the BBC, either on their news channel, or on BBC1, or on a simulcast between the two channels. By contrast, local council by-elections are for obvious reasons never covered live, and indeed are hardly ever mentioned on air after the event. Judging from the complete lack of live coverage of the Shetland result on BBC1, BBC2, the BBC news channel, the BBC Scotland channel and Radio Scotland, it appears that the BBC think that a Holyrood by-election is closer in nature to a council by-election than to a Westminster contest. It's not all that surprising to see London news editors stuck in the dark ages, taking the view that Holyrood is - in the immortal words of Tony Blair - comparable to an English parish council. But BBC Scotland have no excuse after twenty years of devolution, and it's a real dereliction of duty that they didn't broadcast some sort of live by-election special. On past form, it's highly likely they would have done if this had been a Westminster by-election in Scotland.