Boris Johnson's tenure as Prime Minister took another knock last week, with the loss of two very different seats in by-elections, each with somewhat different significance. The first I will discuss, that of Wakefield, is interesting because it is one of the Conservative seats in the historic 'red wall', where Boris Johnson's Conservatives did very well on their route to a majority in 2019. The other, Tiverton and Honiton, in Devon, has been Conservative ever since it was created in 1997, and was won with a majority of 24,000 votes last time.
The loss of each of these will hurt, but the Tiverton and Honiton seat represents the largest majority ever overturned in a by-election, and will hurt the Conservatives hugely. One of the large factors in the victory of the Liberal Democrats in Devon and Labour in Wakefield was that of tactical voting, with Labour doing very poorly in Tiverton and the Liberal Democrats gaining a very low share of the vote in Wakefield. Indeed, it is clear that the disdain held for the Lib Dems by many after the coalition years has started to disappear, and that anti-Conservative voters of all parties are increasingly willing to hold their noses and vote for another opposition party with the best possible chance of defeating them. In fact the Daily Mail was very unhappy about this last week, as you can see below (though in 2019 they did actively encourage the Brexit Party to stand aside in Conservative held seats).
By-elections are useful tools for understanding the current position of the government and all of the parties. In a comment to the BBC the elections guru Sir John Curtice said that it can, however be an exaggerated indicator, as governments always do badly in the mid-term of a parliament. That said, it does also look like the Conservatives have declined somewhat, by as much as 20%, and that no government since that of John Major's from 1992-1997 has had such difficulties. Part of this is, of course, explained by what I said above, and the willingness of Lib Dem and Labour supporters to back each other's candidates.
Tactical voting is, of course, a normal feature of First Past the Post voting systems. Labour tend to do better when the Lib Dem vote is higher, as this tends to be in Conservative areas, and can remove seats from them which hinders Conservative chances of a majority or of being the largest party. For example, Labour got 6,800 votes in Cheadle in 2019, a seat the Conservatives won by 2,300 votes. Likewise, the Conservatives won the High Peak by 590 votes from Labour, where the Lib Dems received 2,800 votes. As you can see, tactical voting would massively assist both parties in these instances. A reduction in Green Party votes in US states such as Michigan may have hurt Hillary Clinton in 2016, and the reduction of these numbers in 2020 may be a recognition of the inevitable impact of First Past the Post.