To understand the British public school system, or certainly, the part of it in which I spent my teenage years, it is crucial to get your head around three things.

The first is that no pupil I can think of left my school fat. Sometimes, a tubby, or even an obese child would step from their parents’ car into the front quad at the age of thirteen. But by the time they left, they would be a sleek, muscular young adult.

The second is that it was only when I arrived at university that I realised I am not short. At five foot ten, at school, I was small. I remember the specific, baffling moment that I was standing in a crowd of my fellow university freshers and saw, for the first time, that my peers didn’t tower over me.

The third is that I know a pair of twins who, when they left, felt such a sense of loyalty to the school they had its emblem tattooed onto their backsides.

How these things happen is not complex.

Glenalmond College – my school

Every afternoon, for at least an hour, and often two, we played sport. I say “played”. It was, particularly in the pre-Christmas ‘Michaelmas’ term, significantly more brutal than that. To warm up before rugby, we would be made to sprint lengths of the pitch until, sometimes, the less fit children vomited. We would lie in the mud with our feet in the air until our stomachs screamed in agony, and, gradually, formed themselves into neat rows of muscle. And then, come rain or hail or ice or snow, we would play.

When we’d finished, we would limp back to our various houses, where we’d boil a large pot of spaghetti, mix in a jar of pesto sauce, and sit round with our peers and a loaf of bread. Using the sliced white to grab, we would swallow handful after handful of oily, salty pasta. Table manners are largely a chain the aristocracy use to tie down the aspirant bourgeoisies.

Soon after finishing this snack, we would go to the grand dining hall, queue up past the names of previous scholars (David Sole, Adair Turner, Rob Wainwright) and collect a three course meal crammed with more carbs.

Outside class, and other than sport, every other waking moment would be filled with some kind of activity. I sang in the choir, played the tympani in the orchestra and the concert band and the snare drum in the pipe band. There were inter-house debating competitions, a school newsletter to write for, school plays in which to perform. In the summer (‘Trinity’) term, I’d spend Tuesday afternoons climbing the cliffs at Dunkeld, and Thursday afternoons kayaking down the whitewater rapids of the Tay. At 13, I learnt to fence. I could, instead, have chosen to spend that time, at the rifle range.

On Wednesdays, it was CCF – the Combined Cadet Force. I mostly managed to avoid it by playing in the pipe band. But I still learnt to stand to attention, march in perfect formation, and to strip, clean and rebuild a gun in under 30 seconds.

Every day but Saturday, we had chapel – the whole school would come together, be preached to by our episcopalian (posh Scots are, in every way, anglicised) minister, and then sing together. We, other than the choir, would sit in pews allocated by house: Skrines, Goodacres, Reids, Patchells, Matheson’s for boys, Lothian and Home for girls.

The chapel at Glenalmond College

It was a matter of pride for our housemasters and housemistresses how loud our respective contributions to the collective musical volume were. My housemaster was choirmaster and organist. His compositions can be found in hymn books across the country. Even for a hardened atheist the effect he conducted, in the glorious, high ceilinged chapel, was majestic and moving. I have often since regretted that every community doesn’t come together each morning, and sing.

On Saturdays, we had assemblies. At these the head teacher (The Warden) would lecture us on something, and then hand out whatever prizes had been won by pupils that week: inter-school shooting competitions, pipe band performances, cross country races and, most important of all, rugby tournaments. And every evening, bar Saturday, it was ‘prep’ – sitting at your desk and doing your homework – followed by TV. In order to stray beyond the ‘front quad’ after these hours, you needed a ‘docket’ – permission slip. All day, every day, every move could be accounted for.

At night, younger pupils slept in ‘cubes’ – cubicles rather like larger versions of those found in a public toilet, with a flimsy wall about 8ft high dividing up each person’s portion of an otherwise shared dormitory. 6thformers would have their own rooms along a corridor, with a desk and a spring-laden bed. Each corridor was governed by a prefect – a ‘beak’. At 17, I was responsible for 13 boys in my year, and fifteen in the year below – for ensuring that they were OK, were quiet during ‘prep’, and, most importantly, that they were in bed on time.

These houses, along with a few of the classrooms formed between them the main school buildings – a front and a back quad designed to mimick those of the most impressive Oxford college – Christ Church. Every 15 minutes, all night long, the bells of the clock tower would echo around the magnificent buildings. After five years, they became a nighttime friend.

Other school facilities varied – on the one hand, music was taught and performed in one of Basil Spence’s finest. On the other, my maths classes were in portacabins and, until my final year (when a new block was built) sciences were taught on the same benches and with the same equipment as they had been for generations.

The final thing to consider is the very fact that this is a boarding school. I haven’t lived with my parents for any significant period since I was 13. Some, if they also went to boarding ‘preparatory’ (prep) schools, left home at eight or nine. If you suspect that this is likely to lead to insecurity then institutionalisation, then you’d be right. DH Lawrence wrote, famously quoted by Orwell, a poem about the upper classes:

“They all gibber and gibber and chatter,
and never a word they say
comes really out of their guts, lad,
they make it up half way…

“When they took you and refined you
they squeezed out most of your guts,
they took away your good old stones
and gave you a couple of nuts,
and they taught you to speak Kings English,
and butter your slippery buts.

Oh you’ve got to be like a monkey,
if you climb up the tree
you’ve no more use for the solid earth
and the lad you used to be.
you sit in the bows and gibber
with superiority…

I tell you something’s been done to ’em,
to the pullets up above…”

Of course, things have changed somewhat since the 1940s. There’s no beating – my school days weren’t those of Tom Brown. But the thing that’s ‘been done’ is still the same. If posh people seem not to be rooted, not to be grounded, it’s because they (we) are untimely ripped from our parents’ home.

I have never seen a study of this collective childhood dislocation, but its psychological effects must surely be significant. It was certainly bizarre for me to meet peers at university had never before lived away from their parents. The process forces you to grow up fast and, I suspect, incompletely: you become tough, but bad at feeling or expressing the healthy range of emotions. Jimmy Reid famously said:

“It is my sincere contention that anyone who can be totally adjusted to our society is in greater need of psychiatric analysis and treatment than anyone else.”

In this case, the products of the public school system – including those who fill the benches of our cabinet and our ‘leading’ banks, should be first in the counsellor’s chair.

The sport, the language, the dislocation, the chapel – all these things may sound odd. But they are typical for a British public school. And I describe them to make a point. Ask most people to outline what their school was like and you would imagine, alongside friends, that they would talk about their classes. But to do so would be to miss the point of Britain’s public school system.

When I went to university, I ended up living with two friends who had both attended Hutchison Grammar – a private day school in Glasgow. We often joked that, whilst they had attended the academically best school in Scotland, I, as an old boy of Glenalmond College – ‘Coll’ – had attended the poshest.

The classes were, of course, good. They were small (10-20 pupils), and most of the teachers were effective. Though some were clearly chosen more for their ability to coach rugby or cricket, and all slotted in to the absurdly posh setting, a few were truly excellent. I found most of them maddening in that they aimed to do no more than spoon feed us with the answers we needed to give in order to get the exam grades to be allowed into Britain’s more famous universities, but the odd one strained at that leash. And that job, at least, they certainly did.

But it is not because you want your child to get top grades that you send them to live for five years at a British public school. There are much easier and cheaper ways to achieve that.

There is a bizarre belief held by many that success in Britain correlates to intelligence and hard work. This is a very middle class concept. What the upper class understands is that success stems from two things: confidence – or, at least, the appearance of confidence, and community. And they are the purpose of public school.

So, all those hours of sport, the diet, the uncomfortable beds – they are all part of a process. They ensure that no one is fat, and that everyone reaches the maximum of their genetically permitted height – that everyone appears healthy, fit.

But more importantly, they are all about team building. These activities exist to build generation after generation who will work together to run a now vanished empire. Whilst the ruling elite might preach rugged individualism, we are brought up to sing together as a whole community every morning, to stand together on the rugby pitch every afternoon, and, after leaving, to go away together to govern India. Each school even has its own, surreal words: ‘docket’, ‘prep’, ‘Coll’, ‘beak’. The more prominent English schools even have their own sports – the Eton Wall Game, Winchester Fives and, well, Rugby Football.

In short, the aim is simple: to build class solidarity. Whilst there are many reasons that essentially the same families have ruled Britain for a millennium, this process of team building, of bonding is surely one of them.

And who were we taught to stand against? Anyone who has met me knows that, despite growing up in Scotland, I have what some call an English accent. I suppose I’d argue it’s better described as a ‘posh’ accent. If you didn’t speak like this at my school, you’d be bullied.

The specific term used was ‘scoit’ – laden with the implications of ‘chav’, but with the bizarre added hangover of the post-1745 crackdown on Scottish culture. Whilst the teachers tried to stop this astonishingly offensive tradition, it lasted throughout my time there – and the school made headlines a few years later when some of its pupils posted online a video in which they claimed to be ‘chav hunting’. So perhaps the oppression has shifted from anti-Scots in particular to just anti-working class. Of course, this tendency isn’t actively encouraged. But the culture of the school certainly perpetuates it.

The middle classes are taught to believe that they will succeed through individual hard work and gumption. The upper class know that this is nonsense – or, at least, our traditions are built on the idea that it is.

And so they teach their children to stick together, to exude confidence whether or not they have a clue what they are doing, to appear physically fit: to form old boys’ networks and to look out for one another. And if you don’t believe this, you just need to visit a British public school, and watch the values being drilled into the children.

The British public school system is best understood not by the brutality of Tom Brown nor by the excitement of Harry Potter – though both do capture a flavour of what it’s like. It is best understood as the root of the British elite. Each school has its own flavour – to the extent that I can usually, at sight, distinguish an OE (an old Etonian), from an ‘OG’ (Old Glenalmond pupil). But they all play a similar function: they build the class solidarity of the British elite. And at that, they are exceptional.

To finish, here are a verse from the Eton Boating Song:

Rugby may be more clever,
Harrow may make more row,
But we’ll row for ever,
Steady from stroke to bow,
And nothing in life shall sever
The chain that is round us now,
And nothing in life shall sever
The chain that is round us now.