Labour Leader Jeremy Corbyn leaves Labour Headquarters, London on June 9, 2017. NurPhoto/SIPA USA/Press Association. All rights reserved.From the Times to the Financial Times, if you read broadsheet accounts of Conservative party responses to their election disaster you can see that it is not just the Prime Minister who is among the walking dead. The whole lot of them are so shell-shocked they don’t know what has hit them – or how short their life-span has become.  There is talk of how good it is that someone as clever as Michael Gove has been put in charge of agriculture because the complications of rural subsidy and food supply “post-Brexit” will be formidable – as if Gove will be mucking out with the farmers for the years to come. ‘The party’, we are told, is ‘not yet ready’ for a leadership contest now – or even in six months. Vicious disputes amongst Conservatives are familiar from the early years of this century. The same fumes of entitlement still waft over from the last one. The Tories, and not just the Tories, believe they are born to exercise power while Corbyn is not seen as ‘serious’. They are in denial.

The most entertaining example of such denial comes courtesy of Peter Mandelson in the Mail on Sunday. Entertaining because he was the most ruthless of the Blairite exterminators, telling anyone who queried even mildly their version of neoliberal globalisation that they were yesterday’s story. Most followers of Tony Blair and David Cameron were confident that they were on the side of history. Mandelson has a special position amongst them: he not only divined the way the cookie crumbled, he crumbled it himself. Only four months ago he said:

The problem with Jeremy is… that he literally has no idea in the 21st Century how to conduct himself as a leader of a party putting itself forward in a democratic election to become the government of our country… Why do you want to just walk away and pass the title deeds of this great party over to someone like Jeremy Corbyn? I don't want to, I resent it and I work every single day in some small way to bring forward the end of his tenure in office. Something, however small it may be – an email, a phone call or a meeting I convene – every day I try to do something to save the Labour party from his leadership.

Two days after the election and writing for millions of readers Mandelson shows us that he is the twentieth century politician. He instructs the ‘moderates’ among Labour MPs to…  support Theresa May! Addressing the prime minister, he tells her she must now show ‘flexibility’ and abandon her ‘head-banging’ version of Brexit. If she does so, then the country ‘will back her’. In which case, Mandelson continues, it ‘would be churlish for people like me and other Remainers not to give her political backing’. This is desperate stuff, conjuring up straws to cling to. There is no mention of Jeremy Corbyn or his achievement. Just this,

Mainstream Labour MPs, who worry about the impact of the continuing Corbyn revolution on centrist voters, should be prepared to stand by the wounded PM, and likewise she should welcome their approach in the national interest.

Only a few weeks ago the whole thrust of Mandelson's contemptuous opposition to Corbyn was that he was incapable of appealing to voters in the centre, thus dooming the Labour Party to irrelevance. Now it is the very fact of his appeal that must be opposed.  Before the election he was deemed marginal, now he must remain marginal. What happened to him in the meantime goes unrecognised.

Denial is not confined to the Blairite extremes. All the cold talk among the Tories as to when to defenestrate May and how long to retain her in suspended animation, is also a form of displacement activity, like Mandelson’s imagining that May will turn to him for advice. The defining reality of current British politics they cannot bring themselves to admit is that Jeremy Corbyn is now the most powerful person in Britain. It is not that he won the election. Labour is still the smaller party. Corbyn's success is that he has changed the nature of the game of politics.

This means that the immediate future of the United Kingdom is in the hands of an allotment-loving, vegetarian, abstemious, republican, peacenik who sticks to his principles. Jeremy Corbyn, a man brave enough to defy the tabloids and tell the country immediately after a terrorist atrocity, that foreign intervention can help stir up the beast of terrorism. His power and authority has three sources, a novel twenty first century combination of old and new: personal integrity, parliamentary arithmetic and popular mobilisation.

His standing, now that he has undergone the ordeal of the election campaign, in a hung parliament makes the nature of Brexit his call. If he wants Britain to have a soft Brexit that is what it will have. If he decides that some form of membership of the EU customs union is essential, then that is what will happen. Should he conclude, as he might well, that it is best for voters to witness the full horrors of an extended Theresa May premiership, then this will proceed. If he is determined that she must go, immediately her position will become impossible.

It is not about who won and who lost the election in terms of seats. Corbyn does not have legislative power. And just as it has flown to him, if it is misuded it can ebb quickly, because of it smoral nature. But, entirely of her own volition, ‘while walking in Wales’, Theresa May took the most momentous political decision a prime minister can and asked the country to demonstrate how it was united behind her. She called for her position to be strengthened, confident that it would be. Morally, strategically and democratically, there is no way back for her now so many voters have declined her call and she is a weakened failure. The Tories can see this about her. What they and the traditional political-media caste are still unable to process is how and why Corbyn has his commanding authority and holds the final fate of May in his hands, as the universe of British politics turns on his decisions.

As someone who did not expect this outcome I am in no position to advise him how best to proceed. He will be himself and we will all wonder at where this will take the country. The first thing to recognise, however, is what he and his team have achieved and the way they have done it. The answer is simple, elemental and yes – just what Mandelson failed to perceive – utterly twenty first century. They have turned Labour from a parliamentary party into a social movement.

The commentariat, trapped by the limitations of its old media platforms and parliamentary expectations, gossips about who Corbyn will promote into his shadow cabinet. This is not without its importance. But he is never asked about how Momentum is organising which is now much more significant. Corbyn's authority is not rooted in his House of Commons support but in his capacity to call millions onto the streets to save the NHS should he say the word.

Social movements are not forces that can be presumed. Their staying power and appeal are in the early stages of growth. For an article that combines experience, witness and analysis of the revolution they bring, see Paul Hilder’s account written just before the UK election was called:

So tear up your old maps. Get out of your comfort zone. Find new allies—or suffer the consequences. Economic systems are failing; old political cartels are losing their legitimacy. Elite populists and democrats are duelling. The need for transformational movements has never been greater—and at last they are rising up.

How did so apparently unlikely a figure as Jeremy Corbyn become the head of a new, defining force in British politics? An important part of the answer lies in the election campaign's manifesto moment, that I will look at next.

Anthony Barnett's, The Lure of Greatness, England’s Brexit and America’s Trump, can be pre-ordered from Unbound to get your advance copy this month. It will be published and in the shops at the end of August.