JEREMY Corbyn is looking like the presumptive Prime Minister of the United Kingdom. A YouGov poll last week put Labour eight points clear of the Conservatives.

It’s remarkable, considering that not so long ago he couldn’t form a shadow Cabinet thanks to a sabotage and smear campaign led by his own MPs. However, it’s now clear that the British elite prefer Corbyn to May or, put another way, Brexit with the DUP scares them far more than the prospect of a social democratic leader, regardless of his “IRA sympathies”.

Corbyn’s movement has been brilliant for English politics, and for the broader international situation where left-wing ideas were rendered irrelevant in European politics by the Troika’s crushing of Syriza. He has broken numerous taboos. Remember the idea that you can’t win the middle class with a left-wing programme? Remember the claim that society has “moved on”, that all that 1970s stuff would never appeal to the younger generation? Decades of nonsense has been cleared aside, leaving England with a real left-versus-right division.

But what about Labour beyond London and the English university towns? For decades, devolution was the plan to make Britain relevant again. Today, like the other New Labour institutions, devolution is dead. Stormont hasn’t functioned for months, and Theresa May’s DUP coalition has probably killed positive prospects of power-sharing. Holyrood has ground to a legislative halt, and remains split 50-50 by the constitutional cold war. May has shut Scotland out of negotations about Brexit, treating our voters like children: you’ll get a say when you vote for a government we like.

Labour is largely frozen out of this crisis. Sure, they know who to blame: they love taking to social media for a gripe about “bloody nationalists”. But this scapegoating neither addresses the failings in British nationalism – our many blood-splattered invasions, the rotten tabloids who set our political agenda, and, worst of all, our obscene Cool Britannia phase – and it doesn’t explain why Labour’s constitutional offerings look so dismally unappealing.

A decade ago, barely anyone predicted this crisis. Indeed, during the anniversary of the Act of Union many commentators noted that, thanks to devolution, Britishness had never looked so strong and secure. So what changed?

Basically, devolution was New Labour’s answer to a British economic and political system that became overwhelmingly dominated by London in general and by its bankers in particular. Rather than challenge this state of affairs, Labour tried to transfer some political decisions to remoter areas: not just Scotland and Wales, but also Northern England. Economically, they aimed to cream off the top of London’s rentier incomes to compensate “the North” for a system otherwise geared to feed London’s growth.

Labour’s fantasy was that the regions would eventually start to imitate the London model, where financiers would do the wizardry (don’t look behind that curtain!) and provide endless cash for politicians to spend. Eventually, of course, peripheral Britain did imitate London, which is why we saw the rapid rise of Northern Rock, RBS and HBOS in the deregulated run-up to 2008.

London’s growth barely blinked after the crash. The oligarchs simply moved in to provide a new stream of income; property prices ballooned again, and the system spluttered on. However, the rest of Britain was left without any purpose.

Then came austerity. Wily Conservatives sought to drastically cut the state without specifically taking responsibility for the impact on social welfare. Devolution proved a useful tool in this agenda. The Liberals and the Tories could pass spending cuts down through the many layers of government, clinically separating them from the consequences of their actions. With cash frozen, devolved parliaments had little to do except turn up the rhetoric on flags and the constitution.

Labour often disdain all this wrangling, but they can’t really complain about nationalism. After all, their position took us into a series of costly and bloody wars for which Gordon Brown was happy to write a “blank cheque”. It all looked so clever in the boom years. Now it’s a mess, and Jeremy Corbyn is basically alone in apologising for Labour’s era of untrammelled imperialism. None of the leaders who draped themselves in the Union flag and voted for it has the courage to address their own role in a major geopolitical disaster.

Putting this aside, constructively, what can Labour offer for the broad crisis represented by devolution? The word “federalism” has been the answer so far. However, when they put forward their proposals last February, they were roundly ridiculed for using the phrase “New Act of Union”. This was actually a little unfair on Scottish Labour, and reflected a default mode of bad temper and cynical mockery that now substitutes for constructive debate in Scottish politics.

Nonetheless, Labour’s proposal wasn’t, in fact, a set of proposals. Instead, it was a call for a constitutional convention that would provide the detail later.

That’s rather unfortunate, because federalism has inherent flaws in a British context that deserve a serious examination. The biggest problem is where it leaves England, because the latter is so much larger than all the other nations put together. London alone, for example, is far more significant in Britain’s political economy than, say, Scotland and Wales combined. Moreover, thanks to London’s growth and devolution elsewhere, the rest of England lacks identity and tends to get ignored, which creates the toxic conditions for the growth of Ukip and other forms of racism.

I’d love to see Jeremy Corbyn become Prime Minister for reasons I hardly need to explain. But he’s got work to do. Britain is a failed project, and putting the pieces back together again is almost certainly impossible. Corbyn can’t delegate the answers to this crisis to the likes of Scottish Labour, because Better Together left them with zero legitimacy among left-inclined Scottish voters.

Only Corbyn and McDonnell have any potential political capital in Scotland. Will they choose to spend it up here to save Britain? Or will they simply reach a tacit agreement with Scottish nationalism? “The crisis consists precisely in the fact that the old is dying and the new cannot be born,” Gramsci famously wrote. “In this interregnum a great variety of morbid symptoms appear”. In this very Gramscian sense, the British constitution is undergoing a crisis that Labour simply cannot ignore.