The problem with the Corbyn project, supporters and opponents have sometimes complained, is not that it is too radical but that it is too conservative. Labour’s 2017 manifesto was hailed as a transformative document but its headline proposals — the renationalisation of water, energy and rail services, the abolition of university tuition fees and higher taxes on top earners and corporations — were redolent of postwar social democracy.

In recent years, the left has rediscovered the politics of futurism. Books such as Paul Mason’s PostCapitalism, Aaron Bastani’s Fully Automated Luxury Communism, Nick Srnicek and Alex Williams’s Inventing the Future, Rutger Bregman’s Utopia for Realists and Peter Frase’s Four Futures argue that technological advancements could render much work unnecessary and liberate humans — sustained by a state-funded universal basic income (UBI) — to pursue a new kind of freedom.

But Labour’s 2017 manifesto was largely unreflective of such thought. It made no mention of UBI, automation or a shorter working week. Added to this, the document promised that a Labour government would deliver Brexit and end free movement. The exhilaration that the left felt at the party’s electoral surge was juxtaposed with quiet disappointment at its programme.

Yet as Labour’s conference closed, many activists were more enthused than at any time since the 2017 election. Beneath the fraught divisions — the botched coup against Tom Watson, the resignation of Corbyn’s policy head Andrew Fisher — the party has endorsed one of the most radical programmes in its history.

The policies backed by conference delegates included a four-day week (with no loss of pay), a Green New Deal (with a 2030 net-zero carbon target), a National Care Service, worker ownership funds, the protection of free movement, the closure of all immigration detention centres, the abolition of in-work poverty and a Brexit referendum in all circumstances. John McDonnell has long promised that Labour’s next manifesto will be “more radical than the last”. The motions passed demonstrated that the party intends to fulfil that commitment. One could call it, as I did in a long read last year, “Corbynism 2.0”.

Rather than merely restoring postwar Keynesianism, or reversing Thatcherism, McDonnell’s ambition is to create an entirely new economic settlement. But Labour’s new policy commitments also draw inspiration from the past.

A shorter working week, for instance, has long been a traditional demand of the organised left. Between 1900 and the Great Depression, the average Western working week was reduced from 60 hours to below 35. In his much-discussed 1930 essay “Economic Possibilities for Our Grandchildren”, John Maynard Keynes prophesied a 15-hour week and concluded that man’s chief concern would be “how to occupy the leisure, which science and compound interest will have won for him, to live wisely and agreeably and well”.

But in the postwar corporatist era, after the experience of mass unemployment, governments and businesses united to revere labour. Nearly 90 years after Keynes’s essay, Britons work an average of 42.3 hours a week, the highest level in the EU (the lowest – 37.8 hours – is in Denmark).

Mindful of this, the TUC recently backed a four-day week within “this century”. But in his speech, McDonell went several steps further, “to reduce average full-time hours to 32 a week within the next decade”. Increased investment in technology, as well as a higher minimum wage (£10) to raise the cost of labour, would accelerate automation and make a four-day week conceivable, the shadow chancellor believes.

Worker ownership funds, meanwhile, are regarded as Labour’s equivalent of Margaret Thatcher’s Right to Buy (as Common Wealth's Mathew Lawrence has writen) – an attempt to forge a new electoral coalition by giving individuals a stake in the economy. Under the plan, private companies with 250 workers or more would be required to transfer 1 per cent of equity annually into the workers’ fund, up to 10 per cent of the total.

The conference also saw the belated birth of what one could call “green Corbynism”. Labour is now committed to dramatic investment in renewables and low-carbon energy, the building and retrofitting of zero-carbon social and council housing, £60bn in interest-free loans for electric cars (and a national network of charging points), rail electrification and the acceptance of climate refugees displaced from their homes by extreme weather.

The programme is, then, unambiguously radical. Whether it is credible is a different question. Economists continue to warn that Labour could not meet its spending pledges by merely raising taxes on the top 5 per cent – it would either need to impose tax rises elsewhere or exceed its current borrowing commitments.

The party is now committed to a Brexit referendum, a major advance on last year, but it has not committed to campaign for Remain. Until it does so, some psephologists warn, it cannot hope to recover lost polling ground and enter government.

Finally, it bears remembering that the policies passed by conference will not automatically feature in the party’s manifesto. The contents of that document will be determined by the party’s hallowed Clause V meeting, where shadow cabinet ministers and trade union general secretaries assemble to thrash out Labour’s election platform.

Some are already warning that several of the most radical policies may not make the cut. “Clause V will knock the bonkers off,” one senior Labour politician reportedly remarked. It is already clear, for instance, that the party leadership does not regard the motion to abolish private schools as workable and will limit itself to removing their tax privileges.

The challenges facing the Corbyn project remain daunting. Even some allies quip that they aren’t sure which to be more worried about: losing the next election or winning it. Every Labour government in history has ended in disappointment, typically having failed to meet activists’ radical expectations.

“There is simply no historical model anywhere in the world for what we want to do which has been successful,” a Corbynite shadow cabinet minister once observed to me. “A left government being elected in a post-industrial society and then successfully managing to transition into a major new settlement, whether a new form of capitalism or socialism.”

But the Corbyn project, sometimes derided as retrogressive, can at least no longer be accused of lacking ambition or radicalism.