We will remember this summer for the rest of our lives. It is starting to feel like a whole decade compacted into mere weeks: despair followed by joy followed by yet more despair, while political certainties that recently seemed rock solid suddenly fall away.

After 10 years of pain, austerity might just be in retreat. The idea of England and Wales as some monochrome expanse, full of nostalgia and nastiness and people content to watch as their social fabric is serially wrecked, has been drastically weakened. The horrors at Grenfell Tower are obviously part of the same moment: a hesitant national awakening in which a sense of dread and worry about where we are headed has been intensified by a sudden realisation about the country we have become.

Clearly, the decisive arrival of Jeremy Corbyn and his new model Labour party has been absolutely central to all this. As it turned out, 2017 was the right time for the restoration of moral clarity to Labour’s soul; the correct point too to leave behind the old, stage-managed politics. As proved by his visit to west London on Thursday, people really do appreciate a politician whose beliefs about the good society are evidently emotional, in the best way. There are now Labour MPs in such renowned lefty redoubts as Kensington and Canterbury. As Theresa May endlessly fumbles, the sense of a leader chiming with his time is powerful.

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There is, then, much to be hopeful about. And among a vocal minority of online celebrants, post-election joy has been accompanied by entirely understandable triumphalism. Haters, doubters and sceptics have been rounded on. Journalists with any history of disbelief or hostility should apparently resign or be sacked. Labour MPs who once wanted Corbyn to quit should be reciting the socialist equivalent of Hail Marys, and burying any hopes of a return to the shadow cabinet. Those who fixated on Labour’s recent losses in local elections or the Copeland byelection are retrospectively deemed guilty of abject pessimism.

Of course, there are media people and politicians whose view of Corbyn and his supporters was hostile and mocking from the start. If they are now switching on their phone to find daily explosions of ridicule and bile, I am sure they can take it: this is the sport they chose. What’s much more questionable is the way the same vengeful attitude is extended to anyone who ever portrayed the last two years of Labour politics in terms of doubt, concern and malaise, and who are being similarly instructed to say sorry for their alleged heresy or be escorted from the building.

Apart from anything else, this jars with the gentle spirit of unity and togetherness – don’t look back in anger, and all that – that has defined so much of the early summer, and which Corbyn has so obviously embodied. Strangely, among the most high-profile voices demanding public apologies are people who only a matter of months ago were themselves portraying the party’s predicament in grave terms and calling for Corbyn’s exit.

The idea of England and Wales as some monochrome expanse, full of nostalgia and nastiness, is serially wrecked

Looking back at the very real woes that preceded the party’s breakthrough, there seems to be some implicit suggestion that a huge crowd of true believers always knew things were on track but could not be heard above the hostile braying. But this, obviously, is not true.

Until May called the election, the Labour tribe remained full of justified resentment about the leadership’s lack of energy and commitment in the EU referendum (and in the wake of 8 June, the question of what full-bore Corbynism might have done to that vote strikes me as a reasonable one). The challenge led by Owen Smith was a content-free fiasco that deserved to fail. But after Corbyn saw him off, plenty of the leader’s supporters had continuing doubts about the future, thanks to everything from his often butterfingered approach to administration, through a big split within Momentum, and on to all those dire polling numbers.

This most self-effacing of Labour leaders would doubtless agree that, even though the Corbyn effect was big, it did not explain everything that happened in the election. In many places, this was a collective and collegiate surge, authored by people inside and outside the party. Labour has a specific and long-standing identity in Wales, which was used to see off the Tory threat in fine style. The same applied in Greater Manchester. As exemplified by what happened in Brighton and Norwich, Labour did well in many places thanks to votes borrowed from the Greens and Lib Dems, whose supporters gladly switched despite the fact the Labour leadership wanted nothing to do with the politics of the so-called progressive alliance. There may have been even more gains if the party had toned down some of its old-school tribalism.

There were also limits to the surge that, as the euphoria subsides, Labour needs to think about. In Scotland, the party put on fewer than 10,000 votes. Despite the “dementia tax”, the Conservative lead among people over 70 was estimated to be 50 percentage points. And the syndrome whereby former Labour voters went first to Ukip and then the Tories was real and widespread – as evidenced by a handful of Labour losses in the Midlands, and other places where the Tory vote went up thanks to voters supposedly at the sharp end of austerity.

To point these things out is not to pour cold water on anyone’s hopes, or to question Corbyn and his people’s achievements. The latter are real, and anyone who thinks of themselves as progressive should have a sense of the election result and its aftermath as a genuine watershed. But the current moment is also replete with tensions and challenges, which is what political commentary is often all about – something that has rather been lost in an age when journalism seems to be losing ground to the kind of partisan shouting that admits no nuances and bounces around from one cast-iron certainty to the next. Looking ahead, one thing above all others is likely to underline the complexities of Labour’s position: Brexit, parked as an issue during the election, to the party’s great benefit, but inevitably set to come roaring back.

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Corbyn’s advance, I have heard lately, is proof of the demise of the politics minted by New Labour and Bill Clinton’s Democrats, and “the end of centrism”. Maybe that’s true; given that this approach had no answers to the huge issues crystallised by the crash of 2008 and a whole set of questions around deepening inequality, that would not be a bad thing. But I suspect that 21st-century politics is much more uncertain, and the way that Corbyn went from zero to hero within weeks is further proof of how politics flips around in a world beyond tribal loyalty, and the quicksilver reality in which we find ourselves.

Events of all kinds now seem to move at light speed. And look at how wildly the political pendulum swings: from Obama to Trump; from the SNP triumphant to Nicola Sturgeon in sudden abeyance; from Europe supposedly in hopeless crisis to the twin leadership of Macron and Merkel; and from the Brexit victory to the glorious shocks and surprises of last week.

As the cliche goes, the election proved that no one knows anything any more. But there’s a drawback: that also includes the people now claiming they alone somehow have the key to the future.