The Rutherglen result does not tell us that Labour will win the next general election. But it tells us they can.
It has long been said that if Labour are to win a General Election, then they must win big in Scotland.
The last time the party won a General Election, in 2005, they won 41 seats in Scotland.
Today they hold just two. Rutherglen's huge 20.4% swing from the SNP to Labour could, if replicated across Scotland, put them back in contention for 40+ seats.
But there are several reasons to be very cautious about believing this will happen:
Margaret Ferrier - this was a very specific circumstance. The outgoing former SNP MP was convicted of breaking Covid rules but clung on until she was forced out by a recall petition.
Turnout - the low turnout in Rutherglen (37%) was not unusual for a by-election but makes it harder to draw conclusions about what will happen when more voters show up in a general election.
Polling - opinion polls show Labour has closed the gap on the SNP across Scotland, but does not have a convincing lead.
If Labour are to win a parliamentary majority they will need to do more than just win seats in Scotland.
They will need to rebuild the 'Red Wall' in the north of England.
Even to become the biggest party they could also do with the Lib Dems taking lots of Conservative seats in the south of England (this looks quite possible).
All that said, if Labour had not won Rutherglen convincingly, it would have been seen as a serious set back to their ambitions.
But they did win, they won big and it is another sign that the political landscape is changing.
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