This hurts. This almost makes me despair of politics. Why invest such emotion, such hope in what a well-intentioned new government can do, only to see it all torn from the roots and trashed at the next roll of the electoral dice?

Twenty years ago, after the euphoria of victory, Labour was already at work on its anti-poverty programme. Tony Blair declared from a balcony on the Aylesbury estate in south London: “No forgotten people, no one left behind.” A Downing Street social exclusion unit created 18 taskforces to explore every hydra-headed cause, symptom and cure for poverty: debt, rents, work, mental health, domestic violence, school exclusion, rough sleeping – and sheer, brutal lack of money.

Soon after, Blair astounded a roomful of economists and social researchers at Toynbee Hall by pledging to abolish child poverty in 20 years – to abolish it! This country, the EU’s near worst for deprivation, would leap to the very top, up there with Sweden? Few in that hall thought he understood what an earthquake in terms of the distribution of wealth, income and opportunity that required. Did he know what it would take for two babies born in the same hospital ward, one poor, one rich, to have equal life chances according to their talent and endeavour? Almost certainly not, but at least the will was there, an optimism that intensive long-term programmes would pay off.

By 2010 Labour had done quite well, leaving a million fewer children in poverty. No government had achieved so much – but it was nothing near poverty abolition. Labour held inequality almost steady: large numbers were raised from the bottom to nearer middle income, but the top 1% soared away unchecked, Peter Mandelson’s filthy rich.

And under this government? The Institute for Fiscal Studies expects a million more children in poverty by 2020. Severe benefit cuts have stripped away the tax credits that powered Labour’s child poverty reduction. Incomes stagnate or fall, with far worse to come as universal credit rolls out. The latest Eurostat figures show nine out of the 10 poorest regions in northern Europe are here in Britain – and so is the EU’s richest place, London.

Tony Blair visiting a Sure Start centre in west London in 2006. Photograph: John Stillwell/PA

All that was carefully designed to reach the Blair target has been shredded or hollowed out. The most farsighted was the great national network of Sure Start children’s centres, 3,500 of them. Finding poor children falling far behind already by 22 months of age, with the gap widening in every school year, Sure Start would help boost them from birth. Now the centres are vanishing, breaking the hearts of all who invested their lives in embedding them into local communities. The time was too short before the great Tory austerity wrecking ball swung.

By this year’s election, Labour had counted that over a third of centres had closed. Now many more are shutting as councils face deeper cuts: money for children’s centres is not ringfenced. Children and Young People Now magazine records the toll of lost centres at an escalating rate. Reading cuts 70%, Hampshire closes 43, Warwickshire shuts 27. Their future is so uncertain, the Care Quality Commission has stopped inspecting them.

There is nothing else here – no pub, no church, no shop, no community hall, no GP surgery

Nowhere needs its children’s centre more than the Wyrley Birch estate in Erdington, Birmingham, one of the country’s most deprived wards. There is nothing else here – no pub, no church, no shop, no community hall, no GP surgery. The nearest bus stop is a mile away. Lakeside Sure Start is the only community meeting place, a fine purpose-built centre, with a cafe, a hub for local services, a base for the police.

But this is one of 26 centres cash-strapped Birmingham council is being forced to close, despite a vociferous campaign and a deputation to Downing Street led by MP Jack Dromey and shadow education secretary Angela Rayner. Julie Doyle, Lakeside’s manager, is a health visitor by training who has worked on Sure Starts from the very beginning, but now despairs at seeing them torn down everywhere. Some are now no more than shells, with just one person and a bunch of leaflets redirecting people to other equally threadbare services, as health visitors and school nurses are cut too. “If we win, another children’s centre will close instead – but who else will shout out for Wyrley Birch families?”

This is the trusted place people turn to for help with everything. Stay-and-play sessions bring in the very young children, with parenting classes of all kinds. Women fleeing domestic violence come here for protection. People discuss debt, work and mental health problems. There’s a pensioners’ lunch club, an after-school homework club, English classes, children’s speech and language sessions, help with rent arrears and activities of all kinds. At its “Xmas xtravaganza” every child had a present, while a Santa sleigh delivered a chocolate bar to every home – for some their only celebration.

Julie speaks of the families who have been rescued from losing their children to care, saving money as well as misery. “One mother was meeting men on the internet and asking them home, which was dangerous for the children. She had no friends or relations, but we’ve helped; her oldest is thriving at school now.” She talks of drawing in the mothers suffering postnatal depression and helping the children failing to speak.

The government sneaked out the latest official children’s centres evaluation a few days before Christmas 2015. The British Medical Journal spotted it, with its embarrassing findings of “positive effects on family functioning and home-learning environments, families experienced a less chaotic home life, and parent-child relationships improved. Mothers using the centres showed improved mental health, and children exhibited greater social skills.” Unsurprisingly, the evaluation found markedly worse results for centres where services and staff had been cut.

Expect Theresa May’s speech at the Conservative conference this autumn to ring with platitudes about opportunity and fairness. Closing the Gap?, the Education Policy Institute’s report released yesterday, estimates that “at current trends, it would take around 50 years for the disadvantage gap to close completely by the time pupils take their GCSEs”. Those who created Sure Start can only despair at the reckless vandalism of shutting down the best chance of closing that gap at the youngest age.

• Polly Toynbee is a Guardian columnist