The starkest sign that the way society’s being run has gone wrong isn’t simply the harm that’s being endured – say, mass child hunger – but the fact that those watching no longer care. For some reason that thought came into my mind this week, as it emerged David Cameron has a “Calm down, dear – it’s only a recession” poster in his £1.5m second home.

“I can’t even afford food or a cot bed for her.” “I worry about making payments, bills …” “We’re only able to feed our children, not ourselves.”

These words are not ideal poster material, but they reflect the reality of families put through one of Cameron’s last policies: limiting child tax credits to two children. New research out this week by the charity Turn2us, seen exclusively by the Guardian, shows almost a third of families affected by the “two child limit” are now struggling to pay for basic living costs. With a new baby to care for but no extra tax credits to help cover costs, parents reported having to skip meals themselves so they could feed all their children. Some told the charity they’re developing health problems because they can’t afford food with the right nutrition or vitamins. Others say their children now have to go without the right school uniform or materials for class.

That cutting tax credits, particularly at a time of high living costs and low wages, would cause harm was predictable – Guardian analysis estimated the policy would push a quarter of a million children below the breadline – but since the policy came into force in April, this is some of the first evidence of the impact of shrinking entitlement to tax credits.

Read parents’ accounts of the change they’ve seen in their children since the income cut and it’s hard to feel this isn’t state-led abuse.

“A sad lonely daughter who has no confidence,” said one. “They’re stressed and sad because we’re stressed and frustrated,” explained another. Others spoke of their own worries – the damage to their self-esteem as a parent who can’t afford even a day trip for the family, or the worry of skipping lunch meetings at work because they can’t buy the food. In the words of one: “[I know] the children see it.”

While the elite laugh at economic downturn, the poor are the butt of the joke. On the same day as the Camerons’ Harper’s Bazaar spread came out, the government released figures showing the number of families having their benefits capped has risen by 214% over the past year. Consider quite how grotesque this gets: since the cap was lowered in 2016, there are now more babies and toddlers hit by the benefit cap than ever before. It’s a testament to the dehumanising anti-welfare climate Cameron’s government helped to engineer that a so-called civilised nation could seek to justify this.

Since the policy’s inception, capping low income families’ benefits has been rationalised by the idea that it “encourages” them into work. But as the recent high court ruling that the policy discriminates against single parents with young children shows, it ignores the way structural barriers – extortionate childcare costs, lack of flexible work – make this almost impossible.

The benefit cap is thus the archetypal austerity policy: one that plays to the post-crash idea of hordes of shirking benefit claimants but in reality, willingly makes the already disadvantaged poorer. As the high court judge put it, it causes “real misery for no good reason”.

The misery is spreading. As in-work benefit cuts bite and living costs rise, the UK is set for the biggest increase in child poverty in a generation. By 2020-21, the Institute for Fiscal Studies projects a 50% increase in relative child poverty, as well as a rise in absolute poverty. The Child Poverty Action Group points out how stark this is in two ways: the increase in relative poverty “will undo almost all of the work done reducing poverty” by successive Labour governments, while the rise in absolute hardship will mean that, over a decade, the income of the poorest families has actually gone down – something without precedent in modern times.

This will be the legacy of Cameron and George Osborne: along with the gamble of Brexit, orchestrating an austerity agenda that amounted to an all-out assault on a whole generation. But to frame this purely in terms of legacy would be a mistake. Legacy implies history – that we are looking backwards, that this is a concern of the past. Four million children – about a third of all the children in this country – are already in poverty. We live in a climate where teachers routinely bring food in for their hungry pupils and kids live out of B&Bs and hostels.

And over the next five years, this will fester, the damage we already see will multiply. Similarly, far from being rid of them, the architects of this crisis are still largely in power. Cameron and Osborne launched policies such as the benefit cap and tax credit cuts but it’s Theresa May and her party who are choosing to continue them. That those governing us can sit back and watch as the damage worsens shows how easily austerity discards the lives of certain citizens.

“Calm down, dear” – after all, they’re only poor children.

• Frances Ryan writes the Guardian’s Hardworking Britain series