So.. is this a one-off or part of a potential new trend in by-elections? From this perspective it looks like a very well organised local protest vote that the Tories will overturn at the next general election.
I think that there's an under-reported trend of the Tory "soft underbelly"
At the moment, reporting Labour's problems gets a lot of media attention because:
a. it fits the agenda of Billionaire press barons
b. Tories want to read about Labour's struggles
c. a lot of Corbynites love to read about Labour struggling (and how "it'd have been so much better if we'd kept Magic Grandad" etc)
But (as I've mentioned before), the Tories have been struggling underneath the radar. They've gone from winning London twice in a row to coming nowhere near in the subsequent two Mayoral elections. Labour winning Canterbury seems to have annoyed the Corbynites more than it annoyed the Tories (since Rosie Duffield is The Wrong Sort Of Labour MP in their eyes). Kensington has a Labour MP. Recent LibDem gains in places like Oxfordshire only got a little press coverage.
But the media focus on Hartlepool, Hartlepool, Hartlepool, which ignores lots of other parts of the country and other narratives.
Johnson is canny enough to hold the disperate wings of the Tory party together for now, because he's good at campaigning (rubbish at
governing but good at
campaigning, which is why he'd rather keep stocking up short term debates about statues than deal with long term problems - remember the promises to deal with the Social Care crisis?). But Johnson isn't going to be around much longer - he wants to be getting big money from his writing - dash of a barnstorming essay for the Telegraph front page for a lot more money than you get paid as a Prime Minister. So where do the Tories go from there? Will Gove be able to assimilate with the humans? Can Patel/ Raab/ Sunak/ Hancock follow Johnson? The Tories weren't able to retain the London mayoralty without him.
But the problem for Labour right now is that... whilst the LibDems were able to attract anti-Tory voters in a traditional Tory constituency, it may be harder for Labour to attract LibDems in Batley'n'Spen - some LibDems are going to feel that Labour is still the party of Corbyn... meanwhile, some people are going to fall for the seductive patter of George Galloway... so it'll be a lot harder for Labour.
Things might be okay for the LibDems though - there's a lot of the Ken Clarke/ Rory Stuart Tories who aren't being represented by the Prime Minister/ Cabinet/ Government - they might keep supporting the Tories at the moment because Johnson is a winner and people like to vote for winners, but any subsequent Tory leader is going to struggle to keep the "wets" and the "Kippers" in the same tent, which means the LibDems could find a good niche, especially if the Tories go for a hardliner like Patel to keep the Kippers onside.