Of the three political earthquakes that have shaken the western political landscape in the past year – Brexit, Trump and Thursday’s general election – the latest has a claim to be the biggest shock of all. Remember that remain and leave were neck and neck in the opinion polls in the days leading up to the EU referendum: a leave win always looked a possibility. In the US, surveys regularly showed Donald Trump just a couple of points behind Hillary Clinton in the popular vote, which is exactly how things turned out.

Corbyn stuck two fingers up at his critics and changed politics for good | Aditya Chakrabortty Read more

But, barring a couple of polls dismissed as rogue outliers, nothing suggested that Theresa May was about to throw away her parliamentary majority. On the contrary, not only did Tory HQ have meticulous seat-by-seat data pointing to a big win, Labour candidates and workers in the field were convinced – right up to the moment the exit poll was announced at 10pm on Thursday – that they’d been thoroughly walloped. Their own face-to-face contact with the voters, whether in Yorkshire or the Midlands, told them they were set to lose dozens of seats. Instead they won 30, including that citadel of socialism, Canterbury.

In other words, politicians and pollsters alike did not see this coming. But nor did most pundits – including me. I opposed Jeremy Corbyn when he first stood for the Labour leadership in 2015, and thereafter, and I did so on two grounds. First, on principle: I was troubled by his foreign policy worldview, with its indulgence of assorted authoritarian regimes, and by what I perceived as his willingness to look past antisemitism on the left. But more immediate was an assessment of his basic electability. I wanted the Tories gone, and simply did not believe Labour could pose a serious electoral threat under Corbyn.

My principled objections have not faded, but Thursday’s results make clear that on the electability issue, I was wrong. True, Labour lost this election, but the party gained seats and a 40% share of the vote. The notion of him winning a future election outright has, suddenly, become plausible. Just as I wrote that Corbyn had to take responsibility for Labour’s disastrous local election results in May, so it’s obvious that he deserves credit for this astonishing performance in June.

Corbyn’s success came about because, while the professional and pundit class were testing his performance and chances against the traditional political rulebook, he took that volume and put it through the shredder. Rule one in that bumper book of conventional wisdom says young people don’t vote. You can generate as much social media buzz as you like, you can knock yourself out with big rallies in campus towns, but it won’t do you any good. The young may share amusing memes, but they won’t vote.

That held true for many years, but no longer. All the evidence points to a surge in youth turnout, one that favoured Labour. The easiest explanation is the transactional one: that Labour’s manifesto promise to scrap tuition fees appealed to younger voters’ self-interest. But it’s clear that something much deeper was going on.

The crowds, the selfies, the tweets were not just indicative of a Milifandom-style cult limited to a narrow few. They pointed to a wave among the young, one that pollsters picked up but then “adjusted” away, assuming it would never be translated into actual votes. Canvassers didn’t spot it: young people are rarely home when volunteers knock on the door. Others assumed that those coming out were merely the Momentum faithful, the same people who’d flocked to Corbyn’s leadership campaigns. Now we know this was much bigger: this 68-year-old man, with few of the natural orator’s gifts, was genuinely connecting with and inspiring the young.

A second tenet of conventional wisdom, apparently borne out by the polls at the start of the campaign, is that Ukip voters are essentially Tories, and that once Ukip ceased to be a viable option, most would vote Conservative. But Thursday’s results suggest plenty of Ukip voters backed Labour. Nigel Farage went on TV to say that he, for one, was not surprised. He’d always known that Kippers were often old Labour types drawn, for example, to rail renationalisation.

It’s clear that many Britons are simply sick of stagnant wages, underfunded public services and unaffordable homes

But there’s another possibility: that voting Ukip was never chiefly about Europe. It was, in part, a protest against the system, one that had let those voters down. With Ukip gone, Corbyn – framed by his critics as a dangerous rebel – looked like an ideal new vehicle for that same anti-establishment impulse.

Divided parties never win elections; that’s a third rule. But Labour somehow won the votes of both those voting Labour because of Corbyn and those voting Labour despite him. Several local candidates told me they were only staying afloat by regularly reassuring voters on the doorstep that they, too, disliked their own leader and would work to see him gone. Meanwhile, and below the radar, younger voters were coming onside, drawn by admiration for Corbyn. The two groups, pro-Corbyn and anti, combined to keep dozens of seats Labour.

There is no more fixed staple of political wisdom than the need for economic credibility. (I still believe that to win an election, rather than just run a respectable second, trust in a party’s ability to manage the economy is essential.) Labour lagged behind the Conservatives on that measure, partly for historic reasons and partly because the manifesto was easily characterised as being packed with too many giveaway goodies to be true. Yet for millions that didn’t matter. After the crash, and after seven years of austerity, it’s clear that many Britons are simply sick of stagnant wages, underfunded public services and unaffordable homes. Putting the case in moral, not coldly technocratic terms, Corbyn successfully framed voting Labour as the only way to say enough is enough.

What of Brexit? The settled view was that clarity was essential. The Tories were for leave, the Lib Dems were for remain, but where was Labour? One analyst quipped that in trying to speak for both the 52% and the 48%, Labour had ended up as the party of the 0%.

Yet Labour’s vagueness seems to have worked. Leavers in Hartlepool stuck with it, while remainers in Battersea came on board too. Each projected on to Labour the Brexit stance they wanted to see. The rulebook, updated in recent years by Lynton Crosby and swallowed whole by his disciples, says it’s impossible to advance from the left, that negative campaigns work better than positive ones, and that the rightwing press is sovereign. Corbyn challenged each one of those assumptions and saw his party make progress.

Lest we forget, it was not enough. Labour still lost, even when faced with the weakest Tory campaign in at least 40 years. But the party surpassed all expectations. Corbyn hasn’t just won 29 valuable seats. He’s rewritten the rules.