By-elections play a strange role in the macro history of British politics. Their significance is often a product of luck, in terms of which seats become available at which points in time, and how that fits with the wider narrative of political events.
Put differently, lots of PMs historically could have been in a lot more trouble if particular types of seats had come up at certain moments in their tenure and highlighted their weaknesses.
When the right (or wrong depending on perspective) types of seats come up, the effect can be huge.
Probably the most famous example is the #Tories losing Eastbourne in 1990. The #LibDems overturned a majority of 16k. Thatcher was gone in 2 months.
en.wikipedia.org/wiki/1990_Eastbourne_by-election
#TivertonandHoniton is a bit different, and that is what makes it even more dangerous. Under normal election conditions, #LibDems would not really be viable, as required swing is too much (Tory majority of 24k).
But it's part of the country where they are strong & there are plenty of seats around it that are genuine targets. So if the #LibDems pull off (or even come close to pulling off) a by-election spectacular, a lot of Tory MPs in the South-West will get very jumpy.
So #Labour and #LibDem inroads might go someway to suggesting that - 6 years to the day after the referendum - the Brexit Wars really are coming to an end, at least in terms of "Remain parties" growing ability to appeal to Leave Voters.
Whatever happens, the headlines tomorrow will inevitably all be about winning or losing. But that is not the key point really. The key issue is the scale of the votes that a moving around within Wakefield, and Tiverton and Honiton.
In isolation, if the Conservatives lose Wakefield by a smallish margin, they could certainly pass that off as being mid-term blues, caused by a protest vote on a reduced turnout.
So look at the size of Labour majority, if they win. That is the figure that matters.
Conversely, even if Tories cling on in #TivertonandHoniton, look for how close the #LibDems get. Obviously, if the #LibDems do take it, that is huge.
The other final very important thing to look out for is the scale of tactical voting, with Labour, Liberal Democrat and Green support coalescing around whichever party is best placed to beat the Tories.
If that's happening at scale, it poses a profound danger to Johnson. A lot of the glue holding this progressive coalition together is visceral dislike of him. It is entirely possible less divisive Tory leader takes some of the energy out of this tactical coalition.
That brings Johnson's continued leadership of the #Conservativea back into question, especially given his only political trick seems to be to double down on culture war politics and to try to refight Brexit, which may only bolster the progressive alliance against him.
So this take me to predictions. Very unscientific, but my sense is that this will be a bad day for the government. I think Labour will win #Wakefield and win it pretty comfortably (maybe a majority of 4k-5k votes).
I also think that #LibDems will win #TivertonandHoniton, and it won't be that close. Maybe a margin of 2k - 2.5k?
This prediction is based on a gut feeling that political commentators are still under-estimating impact of three things:
1. The level of disgust at Johnson's behaviour during lock-down. He remains entirely toxic as a political brand.
2. The real pain cost of living is already inflicting on people.
3. That both sitting Tory MPs left office amid scandal.
Of course, if events do pan out like this, it opens up the practical question about what happens next in the Tory Party, given that they only had a Vote of No Confidence two weeks ago... but that is another question for another day.