Labour leader Jeremy Corbyn visits Whittington hospital. Photo: Stefan Rousseau / PA Archive/Press Association Images. All rights reserved.Whatever happens this summer, Jeremy Corbyn leaves a major legacy. Most notable is the longterm leftwards shift in Labour’s centre of gravity. The party’s right in retreat, Corbyn’s challenger Owen Smith campaigns on an almost identical platform, Trident and the EU aside. Smith’s pitch is to present it better and add much-need policy heft. The course steered may need a new captain, but politically Corbyn binds Labour left for the foreseeable future.

But Corbynism has changed things elsewhere too, and in the most unexpected of quarters. Indeed, the Corbyn Effect may win the next general election. The only thing is, under Corbyn, it won’t be Labour cracking open the champagne. Margaret Thatcher famously named New Labour her greatest achievement. Corbyn’s may transpire to be the caring, sharing ‘New Tories’.

New Labour hatched under Thatcher’s watch, her hegemonic project remoulding 'common sense' in the eighties. But the New Tories sprung when Corbyn’s back was turned. Labour abandoned the business of being an alternative government. Opportunistically, Tories clothed themselves in the garb Labour shed. Their new One Nation Milibandism could be a potent electoral proposition from the natural party of parliamentary rule. And letting the Tories tack left makes a Labour win less likely when one is sorely needed to turn the big, bad Brexit ship of fools back to land.

Labour's slumber as the Tories stole its clothes should come as no surprise. With some exceptions, the left has struggled, since 2010, to get a handle on what Tory modernisation really represents. Railing against right-wing austerity, it ignored Cameron and Osborne's centrist instincts. The left swung blindly at an imaginary hard-right foe.

Pre-referendum, the latter days of Cameron's rule made obvious what they missed. Cameron and Osborne made bold plays for a political centre ground that Corbyn had begun to reconfigure.The National Living Wage is one example. Osborne could afford to alienate a key constituency- business owners- knowing they had nowhere else to go. Current signs suggest Tories wager much the same today. Crabb created buzz with a Keynesian pitch for leader. May comes bearing centrist homilies and a mainly comprehensive-educated cabinet, primed to decimate Corbyn in any snap contest.

Corbyn has opened political space on the centre and centre left. He has also made it possible to talk about austerity and inequality more freely. But he doesn't have what it takes to make hay with it. Corbynism changes the structure of political opportunities, but it cannot contain them. Some, indeed, accrue to the Tories, who have taken full advantage, launching a land-grab for Labour swing votes.

They will succeed in this only in the absence of a clear Corbyn plan to change the wider political calculus in the style of Thatcher. But one does not seem forthcoming. Thatcher came to power with serious intellectual backing from policy think-tanks. She wielded it by reshaping the political and social terrain. New Labour was the result. Blair, too, came at the crest of a wave of big ideas and a popular groundswell of support.

Corbyn’s ascent to the Labour leadership, on the other hand, was a crest entirely without a wave. A fluke victor in a field of also-rans, he rode no surge of public opinion or political revolt. All tip, no iceberg, a limp struggle has since ensued to summon up popular support from nothing. Corbynism has unleashed changes it lacks the strategic resources to convert into electoral success. Smith might.

As Matt Bolton suggests in an excellent analysis, Corbynism has become "as much of a top-down mediated phenomenon as anything under Blair, a simulation of a social movement ". Corbyn’s fanbase, morphed into Momentum, does little to reshape the political lay of the land in its image. Things look different from the doorstep, where Labour old hands bemoan how thousands of corbynista sign-ups translate into one or two door-knockers.

Though it takes on the mantel of a social movement, Corbynism in fact does a better job concealing a crisis of identity. The cult of personality around Corbyn ironically stymies his own ability to succeed. Fixated with his fight against fictional 'Blairites', Corbyn's supporters forget that convincing other people is the only way he'll survive. In this way, the inherent instability of his leadership saps energy from the movement that brought him to power. Petition-signing substitutes for canvassing or street-level activity, when a little of the latter would help shore him up.

But it seems too late. Momentum’s true potential lay in linking up existing social movements with Labour and the trade unions. It could have brought the labour movement into contact with radical experiments in building real alternatives. This would have given practical, concrete form to Corbynism, and, crucially, a life beyond it. Momentum has materialised only with Corbyn’s position under threat. But rallies, marches and meetings for the already-converted are not enough.

For an extra-parliamentary grassroots movement ambivalent about electoralism, Corbynism seems obsessed with party leadership. This paradox is neatly addressed in a recent piece by Amy Westwell. The issue illustrates a historical contradiction for the left. Seeking parliamentary strength can undermine building popular support for social change, and vice versa. With some success, Labour has historically worked within these contradictions. This is something corbynistas seem unable or unwilling to countenance. There are Marxists among them who should know better than to run and hide from contradiction.

For those comfortable with compromise, Labour’s leftwards turn under Corbyn creates a lasting historical opportunity. As Bolton suggests, a new leader from the party’s soft-left could sell the same radical platform with greater success. Owen Smith is now the candidate, but the Corbynist left seem reluctant to seize the chance. For those wrapped in Corbyn-wool, it demands too sharp a revision of existing beliefs. They persist in projecting a shift within the party outward to the people at large, without the legwork that precedes it.

Corbynism may have altered political positioning, but sadly the realities of its salesmanship remain the same. As leader, Smith can take the best of the last ten months- unarguably McDonnell’s economic rethinking – and reach out from the left via a leftwards-listing centre. The post-referendum New Tories, eager to remedy the nation of their party’s EU recklessness, need Corbyn and the political space he affords now more than ever. For the Labour party, Corbyn's radical promise may best be fulfilled with someone else in charge.