This came a lot earlier than I was expecting, and I can't find any coverage at all on TV, but according to North Lanarkshire Council this is the result of the Airdrie & Shotts by-election for the vacant seat in the UK parliament...
Anum Qaisar-Javid (SNP): 10,129 votes (46.4%, +1.4)
Kenneth Stevenson (Labour): 8,372 votes (38.4%, +6.5)
Ben Ron Callaghan (Conservatives): 2,812 votes (12.9%, -4.7)Stephen Philip Arrundale (Liberal Democrats): 220 votes (1.0%, -2.6)
Neil Peter Manson (SDP): 151 votes (0.7%, +0.7)
Jonathan Marc Stanley (Scottish Unionist Party): 59 votes (0.3%, +0.3)
Martyn William Greene (Reform UK): 45 votes (0.2%, +0.2)
Donald Murdo MacKay (UKIP): 39 votes (0.2%, +0.2)
So a closer result than at the 2019 general election, but I don't think anyone in the SNP will be overly worried about that, bearing in mind that their own vote share actually increased. It looks like Labour may have been the beneficiary of tactical voting from Tory supporters - either that or lapsed Labour voters are returning to the fold after trying the Tories out. Turnout is sharply down, which complicates the arithmetic, but it's highly unlikely that the Tories would suffer from that more than other parties, so that's not the explanation for their mini-slump.
This is a by-election that could have been a major problem for the SNP if last week's Holyrood election hadn't gone to plan, because their own supporters would have been demotivated and might not have turned out. However, the good result effectively removed that risk.
It shouldn't go without note that the Liberal Democrats almost suffered the humiliation of being overtaken by the SDP - a party that most people probably don't even realise still exists.