Not entirely sure why a by-election was held on a Monday - it's deeply unnatural, like an accurate John McTernan prediction, or something like that. Anyway, here is the result...
Arbroath East and Lunan by-election result, 28th November 2016 :
SNP 35.0% (-8.8)
Conservatives 27.0% (+12.2)
Independent - Speed 17.2% (n/a)
Independent - Smith 11.8% (n/a)
Labour 6.7% (-6.0)
Liberal Democrats 2.3% (-0.6)
At first glance, that looks like a routine SNP hold on a reduced majority - but as is so often the case with STV by-elections, it's not that simple. The vacancy was caused by the resignation of an independent councillor - so it's technically an SNP gain from independent, even though the independent was 18% behind the SNP in the popular vote in the ward last time around. According to the 'Mike Smithson Doctrine', which ludicrously takes no account whatever of the previous result in the ward, this is therefore a result of unalloyed wonderfulness for the SNP (which is probably why Smithson hasn't mentioned it).
Back in the real world, there has been a significant swing from SNP to Tory, which very much follows the pattern of realignment we've been seeing recently - with Yes-voting ex-Labour supporters in west-central Scotland moving en masse to the SNP, and to a lesser extent No-voting ex-SNP supporters in the north-east moving to the Tories. In a proportional representation election, that swap will always work out quite well for the SNP, but it could potentially lose them a few seats in the next first-past-the-post Westminster contest. In retrospect, it seems a minor miracle that the post-indyref swing to the Tories in their former heartlands was delayed long enough for the SNP to clean up quite so comprehensively in last year's general election.
As the SNP candidate was elected on the sixth count, we're able to see where the various transfers went. It's refreshing to discover that Scottish Labour's love affair with the Tories isn't shared by a majority of their own voters in Arbroath - 31 Labour transfers went to the SNP, and only 18 to the Tories.