Britain’s government has today been held up in front of the world and comprehensively damned for the misery and chaos it has inflicted on its own people. Its defining policy of austerity is revealed to the international community as callous, as ineffective, and even as un-British. These judgments do not come from some well-known foe of Theresa May and David Cameron – but from a UN envoy.

UK austerity has inflicted 'great misery' on citizens, UN says Read more

The profound importance of today’s report from Philip Alston derives from three factors. First, as the UN’s special rapporteur on poverty, he has an international authority. Second, the former law professor has been thorough in his research, visiting all four countries of the United Kingdom and meeting government ministers and those directly affected by their policies. Over 12 long days, he has conducted the kind of listening exercise that Esther McVey could and should have done at the Department for Work and Pensions. And finally, what the UN envoy has seen in this country evidently fills him with fury.

The government, Alston says, is “determinedly in a state of denial” over the national collapse that has been caused by its defining policy of austerity. Whitehall cuts have “gutted” local councils and the legal-aid system. Residents of the fifth-richest country in the world have testified to his team about how a lack of money has driven them to starvation, contemplating suicide or selling sex for shelter.

Over the past few days, Britain has been exposed to the world as possessing an arrogant and incompetent ruling elite, Westminster as a palace of courtiers more focused on their own tacky careers than the country they are meant to be governing. But because Alston has seen what damage this vainglorious ruling class has done to the poorest, the picture he paints of our government takes on much deeper shades of condemnation. For almost half of Britain’s children to be trapped in poverty is, he writes, “not just a disgrace, but a social calamity and an economic disaster, all rolled into one”. If these are indeed the dying days of Theresa May’s government, then its epitaph has been written by a man from the UN.

Rightwing politicians and their allies in the press have closed their eyes and blocked their ears to the devastation caused by austerity. When a debacle such as the one over universal credit becomes unignorable, the right will normally tut and claim it is a failure of implementation; nothing that can’t be put right with a few more quid and some tweaks. But the UN’s special rapporteur on poverty rightly sees something far more sinister at work. The Conservative government’s policies towards the poor have not been driven by economics, he says, but “a commitment to achieving radical social re-engineering”. The Tories want to demolish the last pillars of “the postwar Beveridgean social contract” – and never mind the human collateral damage.

At his press conference this afternoon, Alston delivered this verdict with evident anger and even sarcasm at the wretched ministers. Experts have testified that the system of paying universal credit to one partner in a household exposes women to bullying and abuse – but when Alston put this to McVey, a possible contender to be the next Tory leader, she replied that women “should get counselling and if it gets really bad they should leave”. It is the kind of sentiment even Donald Trump might not voice as being too lacking in human understanding.

Alston has authority but, as he put it to me, “not one iota of power”. But his report is nevertheless a vital tool for the rest of us in holding our government to account and in conveying how a bunch of professionalised, cosseted, smart and cynical politicians have strewn the wreckage of human lives across the country.

And the Australian has spotted something of how Britain has changed this decade. George Orwell is among those who once sang of this country’s “gentleness” and its sense of fair play. What Alston has seen is a society now visiting tremendous violence on its poorest members: those with disabilities, women in poverty, asylum seekers and children. The connection between the brutality of our economic system and the callous, careerist chaos of Brexit Westminster is all too easy to see.

• Aditya Chakrabortty is a Guardian columnist