What happened in the UK between 2010 and 2020 will scar us for the rest of our lives. David Cameron’s Conservatives, only just victorious in the 2010 election, sold austerity as a necessary response to the 2008 financial crash. The exact social consequences of these cuts were spelled out last week in Michael Marmot’s report for the Institute of Health Equity: for the first time in a century, life expectancy has stopped growing and for women in poor areas actually fallen.

We should never stop reminding ourselves just what an astonishing decade we have lived through. In the aftermath of the crash, employment climbed and stayed remarkably high. But these new jobs paid badly and it took until two months ago for earnings to reach where they were before 2008. It is no surprise that debt is mountainous: each household owes on average £15,385, not counting their mortgages. The gap between rich and poor has widened; the young are now worse off than their parents at their age; home ownership has declined steeply – families are stuck in life-long and precarious private renting.

In our 2010 book The Verdict, we evaluated the Blair-Brown era, years of marked social progress. For a new investigation, to assess the extent of the past decade’s damage, we went back to the people we talked to then to see how they have fared since and the hidden ways that austerity has affected their lives.

We followed the fortunes of Emma Percy, in Folkestone, Kent. With her husband, Rob, and three children, the family moved from one rented home to another, changing the children’s schools as rents rose, roofs leaked. They were sometimes living without a functioning boiler all winter long. They were the “just about managing”. Theresa May never got round to helping. Emma and Rob did all the striving and aspiring the prime minister had called for, hoping to save for a deposit, but never quite making enough. In the summer, the only holiday they could afford was camping in the grounds of the school where Rob was caretaker. Their parents own homes; they may never.

Decades take shape in the rearview mirror. Even as the past decade was unfolding, people were aware times were out of joint, an unprecedented number telling a Hansard Society survey at the end of 2018 that the UK was in decline. Everyone saw that pressing national tasks were neglected, as carbon cuts and affordable housing targets were missed, as transport worsened along with education and productivity. Instead, massive efforts were diverted into ideological futility. On the whims of ministers, probation was broken apart, forensic services wrecked and enormous effort wasted on pushing England’s schools out of public control into semi-private academies and trusts, in evidence-free reorganisations.

People expect someone to monitor air and water quality, inspect restaurants and food standards. But the environmental health officers we visited in Huntingdon, Cambridgeshire, were inspecting fewer kebab shops and closing air-monitoring stations despite more pollution. We were there on an inspection when they found a stack of meat pies on the dirty floor of a roadside cafe: the officer told us they register fewer food outlets as high risk, for lack of staff to check them. Nationally, one in 10 takeaways now score zero or one for hygiene and safety. Andy Birks, a butcher in Rotherham in South Yorkshire, told us he hadn’t seen a health inspector in years. “I don’t think there are any left,” he said. Like so many high-street shops, his business had declined in the decade since we first met him, his profits down since 2010.

The Food Standards Agency tests 58% fewer samples and the National Audit Office (NAO) says local authorities are “failing to meet their legal responsibilities”, with staff numbers cut by 45%. Checks that establish if food is safe and contains what it says – not horse meat – were few and far between: the NAO found only 37% of food checks scheduled actually took place. Time and again, in one field after another, we found the covert fraying of the fabric of a civilisation we take for granted.

A Friday night in the control room with Bedfordshire police told the same story of services stretched to breaking point. Mental health and domestic violence dominated the calls. A neighbour reported a man next door banging on his wife’s window, threatening violence. A man called as he chased his son across a dark park, terrified he might harm himself. The chief constable, Jon Boutcher, had just written to his MP recounting a typical night of rapes, stabbings and a lethal traffic accident involving young children. “I run out of officers regularly for 999 calls,” he said.

Meanwhile, the UK got older, with no plan for the decade’s 25% rise in those aged over 65. Social care was a can kicked down the road; as a result, 1.5 million frail old people get no care at all: at the end of the decade, the Johnson government’s response was to deny visas to care staff from abroad, as they earn too little to reach a new £25,600 threshold.

In Hastings, East Sussex, we watched the closure of another day centre, the building sold by the cash-strapped council. This was the seventh of these havens for older adults to close in the town since 2010. As packing cases were being filled with pictures from the walls, we talked to Rose, Mary and Sal, old friends sitting together as they always did, but now for the last time.

Home alone, the statistics showed that many more would arrive in A&E malnourished or dehydrated. That is the constant perversity of austerity; scrimping a bit now to cost more later.

Everywhere, we found a sense of common belonging diminished, with fewer meeting places, playing fields sold off, museums and libraries closed. As the public realm shrank, so did social capital, found the ONS, with less trust and neighbours not talking to one another. Pub closures – premises were down from 52,500 in 2001 to 38,000 by 2020 – were another loss of sociability.

Cameron’s “big society” gimmick delivered a smaller one, as people donated less to charities and volunteering declined. Foreign journalists filmed the Britain of food banks, the homeless, payday loans, bedroom tax and zero-hours jobs. The Conservatives’ pitch in 2010 had been repairing “broken Britain”, but its cracks were widened by an austerity that was neither necessary nor inevitable but resulted from ideological choices. The cap on housing benefit created socially segregated no-go areas for low earners. Councils lost a third of their spending power: buses, planning, housing, youth services and sports facilities were cut or sold off. Nature suffered: Natural England, custodian of flora and fauna in national parks, lost half its budget and shed 1,000 inspectors. Eleven million trees were promised, 1.4m planted.

One service always in the public eye was the NHS. But its 2010 training cuts left it short of 100,000 nurses and doctors. Spending time with the chief executive of Ipswich hospital, we watched as he begged a senior nurse not to leave. Jenny (not her real name), one of his best, brightest and most dedicated nurses, had turned around his difficult chemotherapy ward, caring for seriously ill people feeling at their worst, where deaths of patients exacted a heavy emotional toll on staff. But, taking a deep breath, she told him: “I just can’t keep going.” She would join the nursing bank for occasional shifts, but her departure would add to the 41,000 nurse vacancies. Her team cried when she told them.

The public realm now employs a smaller proportion of the workforce than at any time since 1945. For every £100 for public services in 2010, only £86 in real terms was spent in 2020. Rebuilding schools and hospitals stopped dead. A quarter of local government jobs vanished, with youth workers tackling knife crime the first to go. Criminal justice was hard hit: courts closed; prisons overflowed with violence and drug abuse rife; legal aid was pared to nothing. The armed forces were not spared. Grants to arts organisations fell by a third, funding for national galleries and museums by a half.

It is a perverse society that chooses to harm its youngest most, but years of frozen benefits left families thousands of pounds short, while the old saw their triple-locked pensions rise. State spending per child fell from £11,300 to £10,000. Early intervention for families was so scarce that the numbers of children in care rose fast. Psychiatrists estimated that one in five girls and young women had cut, burned or poisoned themselves in deliberate acts of self-harm on a rising trend: waiting lists for help stretched to a year in some places. Children deprived at school of art, music and drama teaching have lost that chance for ever, with only half taking any arts exams, and trips out severely cut. In 2018, 130 libraries shut and 760 youth clubs closed. This year begins with a million lost young people classified as “Neet”; not in employment or education.

Child poverty soared to its highest level since before the second world war. Infant mortality rose for the first time in two generations. The Thomas Coram Research Institute collected children’s own accounts: “I was so hungry, it was like I got hit in my belly, like I got stabbed with a knife,” 14-year-old Emmanuel told it. The threshold for claiming free school meals halved. More than 2,000 food banks opened, four times more in districts where universal credit – one of the decade’s greatest, but by no means only, disasters – was rolled out. Ministers’ talk of “scroungers” hardened public hearts. In Knowsley, on Merseyside, a food bank organiser collecting donations was asked: “Is this for English people?” He replied: “It’s for hungry people.”

Of course, these years were not monochrome. Plenty of good happened because people are admirably resilient: we found enterprise, generosity and public servants holding it all together with superhuman effort. Despite cuts to subsidies, renewable energy outdid expectations. Film studios flourished, UK acting grabbed glittering prizes and athletes triumphed. But everywhere decaying high streets were a metaphor for national malaise, as internet retail sucked the life out of bricks-and-mortar shops, its US owners paying negligible tax to compensate.

At the other end of the scale, the decade’s winners won big. Jeff Fairburn of Persimmon’s £75m bonus was emblematic; profits poured into his pockets from a misdirected “help to buy” subsidy. Total wealth in second homes, buy-to-lets and flats on the Costa climbed to £941bn. The UK still had more highly paid bankers than the rest of the EU put together. As GDP and pay growth both slowed, profits rose. A third of the UK’s billionaires kept their money in tax havens: the May government backed off from forcing transparency on crown dependencies and, coincidentally, tax exiles donated handsomely to the Conservative party’s 2017 election costs. HMRC cut local offices at the expense of precious local knowledge, a Sheffield accountant told us. Amid austerity, 15,600 tax collectors were dispensed with and the NAO reported 4m calls to HMRC went unanswered; £35bn went uncollected.

British business stayed virtually mute on Brexit, in self-harming silence, fearing public scrutiny of its stratospheric director remuneration, dysfunctional boardrooms and negligent auditors. The small businesspeople we spoke to were often pro-Brexit, refusing to see any bigger picture. A Dartmoor sheep farmer and a Hastings fisherman stayed believers, despite not expecting Brexit to do them much good. A steel stockholder in Derby and a high-street butcher saw turnover drop but stayed true to the faith. Never mind expert reckoning that the Brexit vote was losing Britain £700m a week; taking back control stirred feelings more ineffable than money.

Andy Brooke in Derby had his own bespoke bike business when we first met him, full of hope for the future of his highly specialised service for serious contenders. His shop seemed the perfect spot, near where the council was building a velodrome. But the Brexit vote left uncertainty among his clients from Derby’s big companies. “Overnight, people became very, very careful with their money,” he said. Nationwide, bike sales went down. “Before the referendum, we’d been selling two bikes a week, but now it was down to two a month.” He went bust, his company filing for insolvency. Derby council’s velodrome suffered a similar fate: it made a heavy loss. “This has been a hard time for me,” said Brooke. “I got married and I was busy organising the wedding at the same time as I was dealing with the shop’s bankruptcy.” Looking back, he was rueful. “I was so uplifted by the 2012 Olympics. That showed us off as a great multicultural hub, welcoming everyone. Then came the referendum, so many political lies. Now the country’s creeping in the wrong direction.” So he is emigrating to the US, a young remainer despairing of Britain. “I’ve been offered something in sports science in the US. We want children, but we don’t want to bring them up here any more, not in this atmosphere.”

Brexit was mainly caused by the partisan austerity created by the shrinking of the public sphere by Conservative governments. To win power, Johnson promised to repair his party’s depredations with eye-catching projects. His Brexit rhetoric has raised expectations, but his commitment to “levelling up” is a deceit unless it reverses all the financial and social forces that have been accelerating poverty since 2010.

The lost decade was a Tory decade and perhaps the next one will be, too. They broke Britain; do they really mean to mend it?

• The Lost Decade 2010-2020 and What Lies Ahead for Britain, by Polly Toynbee and David Walker, is published by Faber on 5 March, £10.99 rrp. To order a copy for £8.99 with free UK p&p for orders over £15, visit Guardian Bookshop.

Polly Toynbee and David Walker will discuss The Lost Decade at a Guardian Live event at Kings Place, London N1 9AG on Wednesday 1 April