If this election was bad for the left, it was even worse for centrists. Every MP who defected from Labour or the Tories to the Lib Dems, who signed up to the shambolic astroturf exercise Change UK, who ran as a “principled independent voice for your area”, has lost their seat. The woman who would be prime minister, Jo Swinson, has lost her seat. Had he not stood down shortly before the election, Tom Watson, leader of Labour centrists in the parliamentary party, would certainly have lost his, too.

Centrism has had more than just its personnel eviscerated at this election. During the Corbyn/Brexit “long 2016”, centrism has been nourished by two sustaining myths. The first is that a new centrist party could be a serious challenger to the two main parties. The second is that Brexit support has been on the decline since the referendum. For years now, this is all we’ve heard from centrist sages of both in and outside of parliament. This election proved them wrong. And they’re going to have to find a new line.

Another thing centrists, particularly within the Parliamentary Labour Party (PLP) and Lib Dems, have got wrong since 2016 is to treat since Corbyn’s leadership and the radical left he represents not as a political rival that happens to have the upper hand, but as an illegitimate interloper into British politics. It is one thing to believe that the left would never have a chance of winning an election (plenty of the PLP thought that about Ed Miliband). But when it becomes normal to prefer a Labour loss to a left win, something has gone badly wrong.

Since Corbyn became leader, Labour PLP grandees have been working – indeed, boasted of working – to destabilise Corbyn’s leadership. They have dismissed his economic policies, despite academic support. They have insisted that antisemitism is not merely a problem for Labour (as for the rest of society), but one inherent to the ideology of the far left. Corbyn-sceptic MPs have been permitted to present themselves in the media as disinterested anti-racists, despite their own patchy records on racial prejudice.

Jo Swinson’s Liberal Democrats, meanwhile, ruled out working with Corbyn – and not just in a coalition (everyone does that), but under any circumstances, including a temporary unity government created with the sole policy of revoking Article 50 in order to avoid a No Deal Brexit. Despite being clear that the only route to stopping Brexit was via Corbyn, Swinson insisted the Labour leader was an illegitimate political spokesperson, even as her party signalled its willingness to enter a coalition with Boris Johnson.

In short, centrist politicians and their avatars in the commentariat cultivated the view that Corbyn was ruling his party with ruthless authoritarianism; that he secretly wanted a hard Brexit; that he and his base was overrun with racism. None of this was true of Corbyn – all of it is true of the government we have now ended up with, which received nothing like the same scrutiny.

Given the makeup of the Labour membership, a new leader drawn from the Corbyn wing is likely. If influential centrists retain their view of the Labour left’s illegitimacy and decide to once again delegitimise the new leader, there’s not a lot the rest of us can do about it: Labour members have shown little hunger for kicking out even the most dissentient MPs using trigger ballots. I would implore centrists, however, to recognise how much they lost by treating Corbyn as an enemy rather than a rival.