What more evidence do they need? What more proof do the Labour leadership and its supporters require? This was not an opinion poll. This was not a judgment delivered by the hated mainstream media. This was the verdict of the electorate, expressed through the ballot box, and it could scarcely have been clearer – or more damning.

Win or lose, this will be Theresa May’s last election | Jonathan Freedland Read more

The headline figure is a projected national share of 27%, the worst recorded by an opposition since the BBC started making such calculations in 1981. The Tory lead of 11 percentage points is larger than the one Margaret Thatcher enjoyed as she headed into the elections of 1983 or 1987, when she won triple-figure landslides.

The one-time Labour citadels that fell are jaw-dropping. Labour lost control of Glasgow, which it had ruled for most of the past 70 years. It lost the new mayoralty of Tees Valley – which covers Darlington, Hartlepool, Stockton, Middlesbrough, Redcar and Cleveland – to the Conservatives. Just imagine those towns preferring the Tories over Labour: even two years ago the very idea would have been unthinkable. Labour lost in Merthyr, Derbyshire and the West Midlands – the last a region that in 2015 voted Labour over the Tories by 42% to 33%. Tories picked up seats in some of the most deprived parts of the country, including Shettleston in Glasgow and Ferguslie Park in Paisley.

Sure, Labour won mayoral races in Doncaster, North Tyneside, the Liverpool metro region and Greater Manchester. But those should be givens for a Labour opposition facing a Tory party seven years in office. This is when the party should be expanding, not clinging to its foundations. When the best that shadow chancellor John McDonnell can offer is that the party has not been completely wiped out, you glimpse the scale of the disaster.

Why has this happened? The big shift is the collapse of Ukip – its programme swallowed whole by the Conservatives, thereby rendering the party redundant. Ukip voters transferred en masse to the Tories, reassured that Theresa May will give them the hard Brexit they want. Some of those Ukippers had once been Labour voters, with Ukip serving as the gateway to Conservatism.

But that’s not the whole story. There are, to be sure, some long-term, structural factors at work. Social democratic parties are struggling across Europe and beyond; Brexit has upended everything, so that many working-class anti-EU voters feel better represented by May than by Labour. But there is also a simpler, more glaring factor that cannot be wished away.

Listen to how Dave Wilcox, a former Derbyshire Labour group leader, explains the defeat he and his colleagues have just endured. He heard it again and again on the doorstep: “Genuine Labour supporters said we are not voting for you while you have Jeremy Corbyn as leader.”

He will be howled down, of course, by the online Corbynista army who will tell Wilcox that what he heard with his own ears never happened, that it’s an invention of the media, that it’s really the fault of the media and plotting Labour MPs. But, as it happens, I spent the night before the elections hearing exactly what Wilcox heard – albeit through a two-way mirror, as I watched two consecutive focus groups overwhelmingly made up of Labour voters, convened by the Edelman communications agency along with the Huffington Post, meet in a conference room on the outskirts of Birmingham.

They wanted to vote Labour, they really did. It was how they had always voted. Two men felt they would be betraying their fathers by voting any other way. They weren’t overly impressed by May, though several volunteered that she seemed “strong” (even if all but two of them said they’d never heard the slogan “strong and stable leadership” – a phrase repeated ad nauseam by the Conservative campaign). But they just couldn’t bring themselves to vote Labour.

With no steer from the moderator, who remained studiedly neutral, they described Jeremy Corbyn as a “dope”, “living in the past”, “a joke”, as “looking as if he knows less about it than I do”. One woman admired Corbyn’s sincerity; one man thought his intentions were good. But she reckoned he lacked “the qualities to be our leader”; and he believed Corbyn was simply too “soft”.

Remember, these aren’t metropolitan pundits who the Corbynistas can slam as red Tories. These were hard-pressed Labour voters on middling to modest incomes, explaining why – with very heavy hearts – they were about to break the habit of a lifetime, even of many generations, and vote Conservative.

Corbyn’s defenders will blame the media, but what was striking about these groups was that few of the participants ever bought a paper and they seldom watched a TV bulletin. Corbynites may try to blame disloyal MPs, but, whatever its impact elsewhere, none of that Westminster stuff had impinged on either of these two groups, who couldn’t name a single politician besides May, Corbyn and Boris Johnson. They had formed their own, perhaps instinctive, view.

Blaming others won’t do. Instead, how refreshing it would be, just this once, if Corbyn and McDonnell put their hands up and took even a small measure of responsibility for this calamitous result. Instead of always playing the besieged victim, they could accept that, as Enoch Powell once observed, a politician complaining about the press is as absurd as a sailor complaining about the sea. Navigating a way through is simply what they have to do.

Why are Corbyn and McDonnell so stubborn? It can’t be a tenacious commitment to socialism

It would mean admitting that they have failed to deliver what they promised. They said they would win back Scotland, energise the Labour base, galvanise non-voters, lure back Ukip defectors and pull in Greens – and not one of those things has happened. Yet in the face of all this, they dig in and cling on, refusing to budge.

Why are they so stubborn? It can’t be a tenacious commitment to socialism. Corbyn and McDonnell’s programme includes nothing remotely as leftwing as, say, the £5bn windfall tax on the utilities promised, and implemented, 20 years ago by the supposed evil neoliberal Tony Blair.

Having finally won control of the Labour party after three decades of Stakhanovite effort, what radical programme have these great revolutionaries pledged to the nation? Four extra bank holidays.

The good news for Labour is that what I saw in the focus groups were people unimpressed by the Tories, desperate for an opposition and itching to vote Labour again if only Corbyn would get out of the way. It suggests a new leader could take the fight to Theresa May very rapidly. The bad news is that once people have broken a lifelong Labour habit – and shattered a taboo by voting Tory – they may never come back.