FEW people can be unaware that a great many leading UK figures, particularly those in the Westminster Cabinet, went to public school.

Many, including David Cameron, Boris Johnson and Nick Clegg, were boarders - as were a fair few high-profile Scots, including Andrew Marr, Alistair Darling, Robbie Coltrane, Tilda Swinton and Stella Tennant. At an early age they were packed off to what was often a world of cold dorms, communal showers and little family contact.

In a debate last week at Edinburgh University, psychotherapist Nick Duffell and campaigner Sally Fraser proposed that boarding schools should be banned for children aged under 16. Their argument was less about the social inequality reinforced by private schooling than the fact that, as Duffell has said, the experience leaves boarders "ill-prepared for relationships in the adult world". It also gifts the nation "a cadre of leaders who perpetuate a culture of elitism, bullying and misogyny affecting the whole of society".

Duffell is not alone in believing there is something harmful in the practice of boarding young children. Nearly 15 years ago, the environmentalist George Monbiot described it as Britain's "most overt and qualmless form of child abuse" - saying that it "contravened eight articles of the UN Convention On the Rights of the Child". Recently, even Camilla Parker-Bowles was quoted as saying she regrets sending her son Tom to boarding school. And in a letter to The Observer newspaper last May, Susie Orbach, AL Kennedy and film-maker Don Boyd, among others, called for an end to early boarding, declaring that while "boarding once played a role in preparing men for the rigours and cruelties of an imperial age, our present interdependent world calls for a different, more complex and caring set of values".

The question here is not just whether boarding schools should be banned, but what impact they have had, not just on their pupils but on all of us who live in a country still under the influence of the tradition. I write as someone whose husband was sent away, out of love and with the best intentions, to board at eight years old. I am also the mother of a seven-year-old whom I cannot imagine sending anywhere for very long, not just because it might break his heart but because it might break mine. Having been state school-educated, part of my motivation in writing this piece is to try to understand what it was like for a partner who grew up in a very different world.

It is said that the Spartans invented the boarding school when they began sending seven-year-olds into public education, in a bid to create a well-oiled military machine. Later, Jesuits took up the practice - and the tradition continues in the form of the Catholic seminary. In these modern times, the unique practice of early boarding (the prep school), though it has been exported to our former colonies and other Anglophone countries, is a very British culture. As Nick Duffell, who now lives in France, points out, other European countries don't do it. "It has to do with our class system, with the hidden nature of money, power and influence in our society. It had to do with breeding in an old-fashioned, anachronistic way."

Duffell is a self-declared "boarding school survivor". He came up with the term after years of working as a therapist. "I realised a lot of people are going around ­surviving like they're still nine years old and not ­recognising the difference between a ­scolding headmaster and a loving wife, because actually we were quite traumatised by that."

He doesn't want to suggest that these people are scarred for life: "I'm not ­talking about damage, but about the need to survive, because every child that goes there without a parent has to survive in a peer group with other similarly abandoned children who are all rather afraid."

Duffell's point is that the strategies learned at boarding school are then taken on to later life, where they may not be appropriate. They may, for instance, lead boarding-school alumni to thrive in institutions like the military, banking or politics, but not necessarily in intimate relationships.

Boarding school numbers are not what they used to be. In the 1990s they plummeted across the UK, though they have plateaued in recent years. In Scotland, according to the Scottish Council of Independent Schools, 3375 pupils are boarding this year. That's a tiny fraction - about 0.5% - of the school-attending population and the figures for early boarding are minute: only 15 at age eight, 24 at nine, 56 at 10.

Some may find this issue irrelevant, given all the other societal problems within education and care. But the boarding school question doesn't just affect the privately educated elite. Shetland Islanders are currently fighting a proposal to close high schools on the smaller islands and make children from 11 years old board at a school on Mainland island.

This debate takes place against a backdrop, post-Jimmy Savile and the Caldicott school scandal, of concern over historic abuse. In England, where the Child Sexual Abuse Inquiry causes almost weekly controversy, there's a sense that historic abuses are finally coming to light. Edinburgh-based journalist Alex Renton believes Scotland needs its own historic abuse inquiry. Following The Observer's publication, earlier this year, of his moving recollection of abuse at an English boarding school, Renton received a "lot of letters and emails from people who went to private schools. The problem of unreported abuse in schools in the 1970s and 1980s is as rife in Scotland as anywhere".

Many believe such abusers are enabled by the traumatic effects of isolating a child from their family. According to Renton: "Closed institutions like boarding schools are places where predatory adults can operate with unparalleled access to vulnerable children. And we were vulnerable - emotionally vulnerable - because we had been separated from our parents."

I first came across the idea of "boarding school syndrome" through the activist Sally Fraser, whose children attend my sons' school in Leith. She campaigns for Boarding School Action and writes an eloquent blog, sallyfraserwrites, in which she describes, among other things, how "a couple of years ago my husband seemed to be suffering from more problems than even I could possibly blame on my mother-in-law", and her subsequent discovery of the notion of the "boarding school survivor". She believes the central problem is that, "especially for young children, it's not OK to have them based outside their families. There are lots of people who have shown that it's harmful. Yet we have ­normalised it. And even if it doesn't seem overtly traumatic, and nothing awful happens, leaving home when you're very small changes the way you are".

Fraser described to me how in the past children went through an initial period of non-contact with their parents, a kind of breaking in; letters - often the main link with home - could be censored by the school. Children would be kept active and busy, in order to distract them from thoughts of ­homesickness. I was shocked to find that much of this was also the experience of my husband when he was only a year older than my son.

At the Edinburgh University debate, Fraser spoke for the motion to ban boarding school. She did so as a mother and wife who believes "raising kids in institutions is wrong". Among the research she cited was the work of Royston Lambert who, in the 1960s and 1970s, studied children at boarding schools. "Lambert assessed groups of seven and eight-year-olds: non-boarders and boarders. They were asked to choose a friend they would like to work with for a variety of tasks and challenges, craft, sport etc. The non-boarders all chose the same friend for each activity. The boarders chose different friends for each task. They were already living strategically, had already lost the skill for intimacy, already lost so much of their innocence."

The term "boarding school syndrome" was first coined by psychotherapist Joy Schaverien. Her theory is that the forced separation from family, particularly when very young, represents a trauma - even if the child wanted to board. "A child doesn't know until their parents walk away on the first day what this means," she says.

As a mother, I can only imagine the difficulties of parting from a child in this way. In researching this subject, much of what I heard about the non-contact between child and parent at prep school reminded me of things I've heard about the process of leaving a child at nursery, or leaving a baby to "cry it out". They are denials of instinct and emotion. But then, which parent hasn't, at some stage, pushed their clinging, screaming baby into the arms of a babysitter, only to be told he'll stop crying when you're gone? These days, boarding schools are not the cold, draconian institutions some used to be. They're more comfortable, friendlier, warmer, with more toys and greater family contact.

"It's a lot more family-friendly," says Dr Graham Hawley, headmaster of Loretto, an independent school in Musselburgh, who defended boarding at last week's debate. "The days when children were packed off at the beginning of term and not seen until the end of term are behind us. Families and parents are a lot more involved." One change has been the growth of flexi-boarding, a two or three-day boarding option. Children can, he says, "text their parents, email, talk, Skype, face-time, all these sorts of things".

And some children actively ask to go to boarding school. Eleanor Hervey-Bathurst, an Edinburgh University student who took part in the debate, was six when she asked her parents if she could go to boarding school. She began with flexi-boarding, at "idyllic" Leaden Hall in Salisbury, then stepped up to weekly boarding (home at weekends). From 11 to 18, she did full boarding at Cheltenham Ladies' College. She believes the experience has made her "tougher". Hervey-Bathurst is not easily intimidated, can talk to anyone, and is hugely disciplined. "I'm now training to be in the army. We all have to live in barracks and I think out of everyone there I'm the one who has done everything first, who has ­everything laid out, and I'm calm and collected."

In some ways, in her skill at working as part of an institution, she proves Duffell's point. What's striking about Hervey-Bathurst is that she acknowledges she is a "boarding school survivor" and celebrates it. She also recognises a difference between those who boarded from the age of 11 and those who did so from 16.

She talks of the difficult years, sharing a room when "everyone is in tears because they are homesick", the girls "who dropped out because they were anorexic", the fact that it is "a kind of sink or swim environment". But she sees all this as a positive: it made her who she is. "I come from a traditional, reserved family and I think had I not gone to boarding school I could easily have turned out the kind of person who can't talk about things, who isn't very open. I never hugged anyone. I hated it. And you just can't be that at boarding school."

While researching this subject, I've developed a habit of looking up the school history of people I watch, read and listen to, and have been shocked to find how many are former boarders, including Karren Brady, Nicola Horlick, Jon Snow, Jeremy Clarkson and Stephen Fry.

Things are rather different in Scotland. Holyrood is less dominated by the products of private schools, less elitist. Indeed, Duffell believes "boarding school survivor" attitudes featured strongly in the Scottish independence debate, in the sense that the "bullying" by Westminster and other pro-Union institutions had a distinctly public-schoolish tone. He also believes that "what actually mobilised people was that they'd had enough of that bullying". Given this feeling, he thinks Scotland could conceivably rid itself of boarding schools.

Some may wonder why we should bother about a tiny fraction of the population to whom ­privilege bequeathed boarding school syndrome. When about 16,000 Scottish children are in residential care, why trouble over the trauma of a few posh kids?

One good reason is that these are the people who rule and influence; who shape our culture, politics and economics. For me, there is another reason: the desire to understand my other half. I look at what, at eight years old, he was gifted as privilege. I see my own sons coming up to the same age and I am glad they, and I, will never have to experience that.