The Tories are faced with a pincer movement reminiscent of the one that destroyed them in the 1990s

If Labour and the Lib Dems are both growing in strength, and tending not to cannibalise one another’s electoral base, then the Tories are heading for oblivion

Somehow, Boris Johnson has managed to revive the Liberal Democrats. It’s a long time since the Lib Dems struck a victory quite as dramatic as this one. After their disastrous experiment of coalition with the Conservatives in 2010, the trauma of Brexit and Jo Swinson’s massive misjudgment in giving Johnson his early election in 2019, things didn’t look great for what we used to call the radical centre.

From the largest parliamentary group since Lloyd George, the party was reduced to a Commons rump by 2015. The absurd Swinson gamble – that she and her party could scoop the Remain vote and exploit the unpopularity of Jeremy Corbyn and Labour – left the party just as humiliated as Labour. Now look: two safe seats, Chesham and Amersham and North Shropshire, won back, and smiles all round.

But what do these by-elections prove? First, that the voters are more volatile these days, old habits and allegiances weakened again by a combination of Brexit and, indeed, Johnson’s previous prowess as a campaigner off the back of the 2016 referendum. The habits of voting for one party or another out of habit, loyalty or instinct have dissolved. Mostly it was to the advantage of Johnson and the Tories – the fall of the so-called Red Wall being the most striking and profitable example of the phenomenon for the Tories. But de-alignment, which began before Johnson but which he accelerated, can work both ways, as we see. Conservative voters, in particular, repelled by Boris Johnson and his government, many disappointed by Brexit, are also more willing to rebel, just like Tory MPs.

Second, it shows that anti-Conservative tactical voting is back. Not since 1997 has it been much of a factor, but 2021 was the year when it made its presence felt again. In Chesham and in North Shropshire, the Labour vote was squeezed and borrowed to the benefit of the Lib Dems. In Old Bexley and Sidcup, Lib Dems tended to go Labour’s way. It’s rarely decisive, but it can make a difference at the margins. Where Labour can’t win, such as in tracts of the south west and rural England, their voters can assist the Liberal Democrats to regain the seats they lost in 2015 and after. And vice versa.

Third, then, the Conservatives are faced with an effective pincer movement reminiscent of the one that destroyed them in the 1990s. If Labour and the Liberal Democrats are both growing in strength and confidence, and tending not to cannibalise one another’s electoral base, then the Tories are heading for oblivion. The 10 per cent swing to Labour in Old Bexley and Sidcup was actually the most significant psephological fact of 2021, because it is the kind of huge swing needed to put Keir Starmer in No 10, and it showed that, in the right circumstances, voters will switch directly to Labour, and in volume.

In fact, there is a three-way attack on the Conservatives, because the libertarian, anti-migrant Reform UK, the rebranded Brexit Party, can also take a nibble out of the Tory vote, in this case 3.8 per cent, and that can make a difference in a tight marginal seat (and it did in 2019 when Nigel Farage deprived Johnson of a proper landslide).

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The real obstacle to a majority Labour government is far away from Bexley, Chesham and Shropshire. The party’s critical weakness is in Scotland. There is little sign of Nicola Sturgeon and the SNP being so obligingly repellent as Johnson and the Tories have been.

Not that I’d want to spoil the party, so to speak, but there is a long list of Liberal Democrat by-election wins that revert to the Conservatives (more rarely Labour) at the subsequent general election. Christchurch, for example, In 1993 voted in an excellent Lib Dem MP, Diana Maddock, on a 35 per cent swing only to see her replaced a few years later by a chap called Christopher Chope, who hasn’t exactly been an asset to the Commons.

Liberal “earthquakes” at by-elections have been going on since Torrington signalled the first post-war revival, in 1958 (another Tory loss, regained in 1959). There have been many false dawns. Even so, they do obviously show public dissatisfaction, the “send a message to Westminster” story. So the equally obvious question is whether Johnson can do what is needed to restore his party’s reputation and fortunes by the time of the next general election. But it isn’t as if he’s taking difficult decisions in the cause of a wider identifiable project of national renewal, as it was in Margaret Thatcher’s time when her party sustained gigantic losses to the SDP-Liberal Alliance. It doesn’t feel that way these days.