It is the habit, even obligation, of each succeeding generation to look back with head-shaking disbelief at the practices of previous eras. For most of the 20th century, we could think of the Victorian mistreatment of children – the workhouse, forced labour – with moral superiority. Who could read Dickens and not ask how Victorians were able to stick little kids up chimneys?

But in demonising the past, there’s always the danger of ignoring the problems of the present. The widespread abuse of children by Catholic priests went on for decades without any concerted effort to punish or prevent it. Equally, the horrendous cases of organised grooming and sexual abuse of young vulnerable girls by Pakistani heritage gangs in cities around England continued for many years while the authorities turned a blind eye. By the same token, the plight of children in “care” continues to shame us. And, believe it or not, as recently as 1998 it was legal to cane young children in independent schools in England and Wales.

That last incredible fact features in Stiff Upper Lip, Alex Renton’s powerful study of abuse – physical, psychological, sexual – that has been a feature of boarding schools pretty much since they were created. The book stems from a piece Renton wrote three years ago for this newspaper’s magazine about his own experiences at Ashdown House, a boarding prep school that also educated Boris Johnson and Viscount Linley, among other well-known people.

It garnered an overwhelming response from men and women who had spent the greater part of their lives dealing with the traumas they suffered as young children in the care of trusted adults. Renton cites many of the stories he received, as well as quoting various famous figures, including Winston Churchill and several members of the Waugh family, who have written about the horrors inflicted upon them at a tender age in boarding schools.

Of course, the first horror is enforced separation from parents. As Renton notes, no other culture does this either so early or for so long. In other words, boarding schools are unnatural – certainly for pre-teenage children. There are many cases in the book of children being sent away to school at four years of age.

Leaving aside other torments, the psychological damage wrought by separation from parental, and particularly maternal, love is clearly life-long in many cases. Renton quotes individuals who, long into adulthood, are incapable of forming loving or trusting bonds with anyone. But he also describes a culture that makes light of it all, through shared jokes, class-based rituals and a kind of snobbish pride.

How else could institutionalised suffering have been allowed to go on for so long with so little protest? After all, children were frequently sent off to schools where their own parents had been traumatised or abused. In some way, they had internalised their dark, lonely times and accepted the idea that it was the making of them.

That’s one explanation. Another is that some parents didn’t care about their children, or felt that whatever punishment they endured was fit and proper. Take the case of Richard Meinertzhagen, a first world war British spy and military hero. His mother was one of the Potter sisters – another was Beatrice Webb, the Fabian social reformer.

As an 11-year-old, Meinertzhagen was regularly beaten bloody and blue by a sadistic master, but his mother, who believed in emancipation of the lower orders, ignored his pleas, telling her son that he must have behaved very badly.

There are many such published accounts, but they did little to dampen the desire of parents to send their young ones away. And when boarding schools did start to dip in popularity, they came back into fashion after the mythologising effects of the Harry Potter series.

Renton, and other investigators, estimate that as many as half of Britain’s private schools have harboured paedophiles in recent years. During the same period, historic cases of extensive teacher-pupil abuse have come to light, leading to a number of criminal cases and prison sentences.

There is, of course, post-Savile, a much greater awareness of child abuse, and of how cunning and persuasive established abusers can be. But it’s fair to say that there hasn’t been an overwhelming public concern for the plight of privileged children in expensive private schools. The victims – or survivors – often go on to be outwardly successful people, confident, articulate and seemingly powerful, though there are plenty of examples of individuals who never recover.

Why isolate their suffering, runs an argument, when children in care – who are hugely over-represented in prison, drug abuse, and in all other markers of social dysfunction – are overwhelmingly voiceless?

Renton is perfectly aware of this line of thinking. His answer is that if the ruling class can treat its own children this way, what hope is there for those less fortunate? I’m not sure that it stacks up as a response to the criticism of privilege, partly because I don’t think the criticism is valid.

Although there are doubtless many children who are worse off than the unhappy elites sent off to such places, the boarding school – particularly the boarding prep school – is a distinctive British institution that has a long and tawdry record as a safe space for sadists and child molesters.

Naturally, there are many schools that don’t deserve to be roped in with the worst offenders, but few that have not been the scene of the most awful childhood loneliness and anxiety.

As Renton shows, boarding schools were once seen as the first step to creating people fit to run an empire. That imperial self-justification has long been out of date, but something of its spirit lives on in the belief that removing children from their parents is the best way to prepare them for the rigours and demands of a fulfilling life.

By the end of this thoughtful and sensitive indictment of one of the cornerstones of the British establishment, it’s very hard to conclude anything except that generations of children have been emotionally damaged on a truly shocking scale.

That these people have often gone on to occupy senior positions in politics, the military and the judiciary should, at the very least, give us pause for thought.

Children do need to be stimulated and challenged, and often today they are overprotected. But they also need the love and affection of concerned adults. Take that away and anything becomes possible, including the attention of adults who should concern us all.

• Stiff Upper Lip by Alex Renton is published by Weidenfeld & Nicolson (£16.99). To order a copy for £14.44 go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99