Massive 21% increase in vote share for pro-independence parties in the Fort William & Ardnamurchan by-election

So I’m quite excited to be able to report on a local by-election result from a ward I spent a couple of nights in during the summer, although it’s so geographically enormous that probably quite a lot of us have been there recently! While the Westminster village was preoccupied with a routine Tory hold in Sir Edward Heath’s former constituency, for Scottish politics-watchers yesterday was all about Fort William & Ardnamurchan.

Fort William & Ardnamurchan by-election result (2nd December 2021):

SNP: 39.6% (+6.7)

Conservatives: 21.2% (+8.5) 
Greens: 14.3% (+14.3) 
Liberal Democrats: 10.1% (+5.5) 
Independent – McKenna: 8.5% (+8.5) Independent – Matheson: 3.8% (-0.5) Independent – Drayton: 2.4% (+2.4)

Almost every time I report on an STV by-election result, I have to explain that things are not quite as they seem – the result might be billed as a “hold” for a party that has jumped from second place to first in the popular vote, or as a “gain” for a party that has merely remained in first place in the popular vote.  Our old friend Mike Smithson was left red-faced after misunderstanding that point on one celebrated occasion – and he’s a renowned letter-writing totally objective Liberal Democrat election expert, so it’s very easily done.
Fort William & Ardnamurchan is a particularly complicated example, though, because yesterday’s result is technically an SNP gain from the Conservatives – in spite of the fact that a) neither party topped the poll last time around (an independent candidate did), b) the SNP were well ahead of the Tories last time around, and c) there was actually a small swing from SNP to Tory yesterday.
The percentage increases that all of the parties enjoyed can be mostly explained by a large number of votes that went to the victorious independent candidate in 2017 being up for grabs this time, and splitting multiple ways.  That said, the SNP are still entitled to regard their own increase as impressive, if only because it was achieved in spite of a Green intervention – in other words they didn’t face competition for the pro-indy vote in 2017, but this time there was competition and it was remarkably stiff.  The combined vote share for the pro-indy parties is actually a whopping 21 points higher than it was four years ago.