LEFT and Right in Britain hate each other in different ways. The Labour Party have naturally always loathed the Tories ("lower than vermin", as Aneurin Bevan put it). At rare moments, they have dreamed of frog-marching the Tories to the dustbin of history and slamming the lid down. But on the whole they have hoped that "history" – a spreading awareness that the Conservative Party and its policies were a faded joke – would do the job for them. Meanwhile, Tories safely kept in their box had to be lived with.

Tory attitudes to Labour and the Labour movement have been something else. They are often about exterminating, wiping out for ever. Margaret Thatcher was explicit: socialism had to be uprooted from British soil and burned like alien knotweed. Winston Churchill, in spite of his wartime coalition with Labour, had never ceased to suspect the left as rootless, treacherous Bolsheviks. And Theresa May is no better.

Her strategy in this election was simple and shocking: to defame and abuse the personality of Jeremy Corbyn by day and night at the expense of discussing policy. Anyone watching Parliament TV since she became Prime Minster has registered the real hatred as she pokes her head forward across the dispatch box to jeer and sneer in Corbyn’s face: no leader, no grasp, no patriotism. A repulsive performance. But she longs to stamp out the whole jihadi-hugging, Britain-loathing and – worst sin of all – disobedient movement he heads.

Simple and shocking – and unsuccessful. On Thursday, in spite of the worst-ever tabloid monstering which came close to urging "our nation" to lynch Corbyn, the hatred backfired. He didn’t win. Labour lost. But this mild and obstinate fellow – everyone’s old geography teacher – confounded all prophecies and brought his party within (distant) sight of leading a government. Theresa May had been so sure of herself that she mockingly invited audiences to imagine Jeremy Corbyn as Prime Minister. Some of them did. So now May is politically a dead woman walking.

Before the election, the usual choir tuned up their favourite lullaby: left and right are so over, so 1960s, now we think in categories of millennials and boomers, somewheres and nowheres. But it turns out they aren’t over. They are planted in facts which don’t age. The fact that the strong will always oppress and exploit the weak if society doesn’t stop them. The fact that "the poor have no lawyers". The fact that uncontrolled capitalism consumes its sources, its labour, its environment and eventually itself.

Left is Jimmy Reid looking up at windows in Govan and knowing that men who could have driven like Lewis Hamilton, women who might have mapped DNA like Rosalind Franklin, live unrealised behind them. Right is saying "Now is not the time", or "Suppose everyone wanted it", or "Governments only make things worse".

That is the sense in which the left in Britain began to revive under Corbyn. Nigel Farage was perfectly right, the morning after the election, to be impressed at how he had taken the EU Remain vote in London and the Leave vote in the English north and Midlands. Another way of putting it: Labour sucked up the Ukip vote in parts of England like post-industrial Yorkshire, where people could never dream of turning to the Tories, to the "Thatcher party" which destroyed their jobs 30 years ago.

Socialism? Not really. Labour’s programme under Corbyn was a decent social-democratic agenda, much of it resembling SNP policies already applied or projected. But it was packaged in a far more determined, attractive bundle. It was hardly "extreme", even if some items – like the re-nationalisations – might have conflicted with the current EU phobia about state support and insistence on unrestricted competition. It could have been an updated version of a manifesto by Jim Callaghan or even the early Tony Blair .

After all the moans about political apathy, it was a surprise that within a few days of publication large numbers of people seemed to know something about the Corbyn manifesto. Programmes, issues and policies are in. Voters, or at least a significant number of them, want to know about manifestos and have been paying attention to the party campaigns. What’s out is person-led sloganeering.

May entirely missed this. She had started off by talking about the good things a state could do and the weakness of free markets, and the public had shown some interest. But in her election tours she merely droned on about "strong and stable" and the flaws in Jeremy Corbyn. Many of her listeners wanted coherent accounts of Conservative policy on social welfare and Brexit. They didn’t get them and felt they were being treated like idiots. It was this, rather than the gaffes about social care, that made her campaign such a disaster.

So far, this change of public interest towards campaigns and manifestos has helped the left ( as well as reassuring cold, wet canvassers that they are achieving something). Nobody who agreed with Brenda about elections ("For Gawd’s sake, not another one?") expected the big turn-out of the young, who gave Corbyn’s rallies the sort of noisy passion which Labour used to show many years ago.

Can it last? Does Corbyn’s impact on the public as well as on party activists mean that a more left-wing Labour Party might one day be elected? There’s a chance that it could. A space has opened for it. The free-market dogma created many losers and few winners all over Europe and America. Now it’s in decay. Normally it had been socialist and social-democratic parties which took the cause of the losers, but almost all of them, including New Labour under Blair, had defected to neo-liberal policy. That left a vacuum. Into it rushed populism – movements which were violently nationalist, authoritarian but also protectionist on behalf of the working-class millions cast adrift by callous Reagan-Thatcher doctrines: Marine le Pen, Donald Trump … and Nigel Farage. But Ukip is different: so far, it's the only new populist movement to collapse. And Corbynite Labour has walked straight into that constituency, the land of zero-hour contracts and a young generation with less opportunity and income than its parents.

Can it win? Yes, it can but only if it’s skilfully led – Corbyn is better at crowds than colleagues. (The same space once lay open for Labour north of the Border. If they hadn’t been so blindly thirled to the Union Jack, Labour would have long since overtaken the SNP and would today be heavy-lifting the problems of an independent Scotland.)

There is a job now for the left throughout Britain. If only they had noticed that before.

Neal Ascherson is a journalist and author