If I wanted to save capitalism, I would prioritise social mobility. Not Jude the Obscure-style mobility, where it happens over generations, but the kind we achieved in the postwar era. The kind that sent orphan, gang member and naval rating Bernard Schwartz to acting school to become Tony Curtis. The kind that makes things better in your lifetime and, in fact, in your first decade as an adult.

I know this kind of social mobility is possible because I am a product of it. My paternal line on Ancestry.co.uk reads: hatmaker, hatmaker, hatmaker, miner, miner, economics editor of Newsnight.

What made the difference? In the rightwing version of my life, the explanation is that I was sent to grammar school. Five boys out of a class of 30-plus selected by examination to be taught Latin by priests instead of woodwork by bored laypeople. But plenty of my classmates ended up “back” in the working class: as police sergeants, office drudges or military personnel.

No, for me, grammar school was just the sharp tip of an arrow pointing upwards that was created by an entire economic system: the postwar Keynesian settlement. If I look at a picture of my dad as a schoolboy in the 1930s – partially deaf and among the poorest kids in the class, destined for the pit like his own father – and then think about him discussing Solzhenitsyn with me in the 1970s, I can understand that upward social mobility was a long process; a culture; a collective effort.

My father lived through the thing that terrified Richard Hoggart, in The Uses of Literacy, and then Eric Hobsbawm: the decline of the implicitly brutal and subliterate “proletarian way of life”. Watch a movie such as Saturday Night and Sunday Morning or This Sporting Life to understand the yearning for improvement, non-brutality, tenderness and advancement that gripped working-class people in the 1950s.

This, in turn, had material roots: cheap rents, free education, aggressively interventionist social work against dysfunctional families, TV stations run by philanthropists rather than, as now, people determined to promoting ignorance.

If I wanted to save capitalism, I would tell Theresa May to implement all this urgently – and more.

She is not listening, of course. The government’s entire social mobility commission, led by Alan Milburn, quit last weekend, days after penning a sombre report warning that “Britain is in the grip of a self-reinforcing spiral of ever-growing division”.

Not “getting better”, not even “limiting the damage and stabilising things”, but fostering a self-reinforcing process whereby poor kids are trapped in poverty for ever, certain that their own kids will be just as poor and probably even less likely to break out of poverty. One of the most depressing things about Milburn’s final “state of the nation” report was the maps. Industrial towns such as Wigan, where I grew up, are low-to-middling when it comes to the overall picture of decline. The real blackspots are predictable entirely through geography: the off-the-network seaside towns, the places you can never quite remember between two motorways, the rural areas, the extremities – these are the places where social mobility is appalling. If it were not for London, cranking out literate, worldly teenagers from its comprehensives and estates, there would hardly be a social mobility story at all.

The irony is that, when we were kids, every Saturday evening was spent listening to a list of these places being read out, as a kind of egalitarian national roll call, in the football and rugby results. Mansfield, Motherwell, Colchester, Llanelli – places you would never actually visit, but could be fairly sure were being looked after because a plummy-voiced BBC man was reading them out, week after week, in the same breath as Manchester United and Chelsea. Milburn’s report provides the clearest reminder that this national story of upward mobility has been shattered.

And by what? The neoliberal economic system didn’t start out trying to suppress the upward mobility of working-class kids. But that is what it has achieved. Blairism momentarily checked the decline, but it is back now with a vengeance. You can point to austerity or to objective factors such as the decline of semi-skilled manual work – but at the policy level it is just neglect.

Every headteacher is judged on the improvements they make for individual children, yet the government is never judged against the neglect and cruelty through which it makes the poor powerless and traps the talented in layers of indifference.

You could buy this sick system a few more years if you dropped all other obsessions and concentrated on getting a chosen few poor kids out of poverty. That’s the intent behind all the schemes aimed at getting poor and ethnic minority children through the barriers of the Russell Group universities. But nobody in government appears to care enough to fix it. They care a bit – but not as much as, say, reciting Kipling’s Mandalay in a Myanmar temple, taking holidays in Israel or rescuing colleagues who have committed sackable offences.

As Milburn put it in his resignation letter, the government does not have enough bandwidth to do what Labour and Conservative governments after the war were obsessed with – making sure a minority of working-class kids break out of poverty.

People ask (and rightly) what it is that Jeremy Corbyn has to do to seal the deal with the British working class – even now wary of Labour in big enough numbers to keep the Tories neck and neck. I know what cemented my dad’s generation to capitalism: a culture of social mobility; the rising possibility of self-improvement; an upward curve; a cheeky optimism.

Your kids will go to university; they will get a toehold in the housing market; their wages will rise; things will get better for everybody: these were the promises on which Labour sealed the deal with the postwar working class. That they seem like Bolshevism now, in the era of May and Rees-Mogg shows how difficult it will be to revive them and how tired British capitalism has already become.