“Golden rule number one is that we don’t talk to the press,” the headteacher says. But then, gradually, eventually, with persuasion, this is exactly what he agrees to do.

First, however, he lays down the ground rules. There are to be no names: not his name, not the name of the state school he heads, and not the name of the child he will, tangentially, be discussing. Certainly, there will be no reference to the name of the child’s father: a name that is likely to be heard, on a fairly regular basis, in households across the country.

“You won’t mention the child or the school,” he says. “Because, if you do, I will come down on you like so many very heavy bricks.”

No one gave him these rules. There is no module in teacher training college on dealing with the offspring of famous parents; no government pamphlet offers guidelines on coping with autograph hunters at parents’ evenings. Earlier this year, when news broke that David and Victoria Beckham would soon be sending their three sons to school in Hertfordshire, staff at the school in question had only their own common sense to rely on, in order to prevent gathering crowds of paparazzi, football groupies and prepubescent girls, all desperate to catch the junior Beckhams kicking a ball around the playground.

Indeed, this is something that teachers must work out for themselves. The unnamed head - pseudonymously Mr Lyon, protecting his young cubs - has spent considerable time on this, drawing up a set of rules that determine exactly how he will act, as long as the celebrity offspring is under his charge (see box).

First of these rules is the need for absolute media silence. Mr Lyon takes this to its logical extreme, refusing to make any statements to the press, even on subjects unrelated to his celebrity parent. “In the past, if the Government did this, that or the other, and I disagreed, I might have spoken to the press, told them I disagree,” he says. “Now I don’t because my opinion gets attached to the child.”

In a world where celebrity is synonymous with credibility, the name of a famous parent adds weight to the opinions of an otherwise unknown headteacher. “So I will not talk to the press,” he reiterates. “That’s the secret to managing a famous child in the school.”

But however low the profile one keeps, there is always the possibility that word will get out. And so the school needs a contingency plan. “There may be security issues,” says Mr Lyon. “If it is public knowledge that a famous child is at a particular school, that school will have problems. It depends on the child, depends on the fame. The school just needs to do a risk assessment, look at whether or not it needs to increase security levels.”

Mr Lyon invited third-party specialists to review his school’s security measures. In fact, their report revealed that the school was already secure - there was no need to do anything more than the school had been doing already. “If I just say `77’, that should be enough,” he says. “Whether or not you have a famous child in a school, security needs to be good.”

Similarly, there are no special confidentiality agreements, no staff instructions about careless talk costing careers. “Staff don’t talk about children in the school with anyone outside the school,” he says. “All schools will have that rule because it is part of the child-protection policy. The confidentiality policy is made clear to staff every year at our yearly review, a staff Inset day.

“But we don’t discuss any of this with the celebrity parent,” he adds. “Working with a famous person is the same as working with any other person.”

This is echoed by Tony Little. Mr Little is headmaster of Eton College, the alma mater of significant numbers of celebrity offspring, including the crown princes of Nepal and Jodhpur; Ben and Zac Goldsmith, sons of billionaire businessman James; and generations’ worth of Parker Bowles. “You deal with parents as parents and boys as boys,” he says. “It doesn’t matter what their perceived status is.

“People have particular sensitivity about the protection of children, and one can understand it. But we are what we are. We have a fairly open site. If you have a family that wants a particular type of security, that is not going to happen. We have had requests, and we have had people not send their children here as a result. It is kind of self-selecting in that way. We want every boy to have a similar experience, and to be treated in a similar fashion.”

The only time there has been an exception to this rule has been when Eton admitted possibly the best-known celebrity offspring of the modern era: Princes William and Harry. In this instance, additional police were allowed on site to monitor their charges’ moves.

Security, however, merely serves to keep out outsiders: it seals off the school from prying eyes and long-range zoom lenses. It can do very little to fend off interest from those who are actively invited into the school: teachers, parents and other pupils. And any illusion of normality is difficult to maintain when an Oscar-winning actor is standing in the queue at parents’ evening.

“Our parents’ evenings involve individual appointments,” says Mr Lyon. “So we don’t have a whole crowd of parents milling around in a hall, listening to everybody else. And there are no reserved seats at our school plays, ever. If the famous parents don’t turn up on time, they have to fight for a seat along with everybody else.

“If the parents keep a low profile themselves, if they don’t put on airs and graces, don’t expect special treatment, then it’s not an issue for other parents. If you treat them as normal, everybody else does.”

Alyson Russen, head of Millbank Primary in Westminster, agrees. For three years, she counted Gordon Brown’s son John among her pupils. From the start, she says, the Browns acted like any other parents at the school. They were seen so regularly that they quickly ceased to generate any interest.

“I don’t know if there is a difference between politicians and actual celebrities,” Ms Russen says. “Someone like David Beckham or Cheryl Cole - you are meant to mob them. But, with politicians, you are not supposed to scream and mob them. That is not how we act around them.”

David Levin, headmaster of City of London boys’ school, believes that a famous face in the school corridor often attracts little more than a sideways glance. “Y’know what the English are like,” he says. “Precisely because there is a frisson around a famous person, they go remarkably shy and indifferent. They don’t want to be seen as gushy and intrusive.”

City of London’s famous parents range across the celebrity spectrum. The school has educated the son of actress Sadie Frost and Spandau Ballet guitarist Gary Kemp, as well as the children of Russian oligarch Boris Berezovsky, one-time lord chancellor Lord Irvine, and the current Bishop of London.

But if there is any excitement among teachers about their famous-by-proxy pupils, it is short-lived. “Inevitably, there is curiosity around a famous parent,” Mr Levin says. “But classrooms are busy places. We have got lessons to teach. We have just to get on with it. Any novelty value, in my experience, is gone within a day or two.”

Besides, he insists that it is crucial that all boys are treated the same, regardless of wealth, race, religion or celebrity status. Mr Little agrees. “We want every boy to have a similar experience, to be treated in a similar fashion,” he says. “We would never flag up a particular boy, whether his family home is a tower block in London or a castle overseas.”

This, in fact, is another of Mr Lyon’s golden rules: a sense of normality should be maintained at all times. And it is repeatedly echoed and emphasised by every other headteacher, too. “The pledge we gave the family was that we would treat the child like any other child in the school,” says Ms Russen, John Brown’s head. “They desperately wanted that. The child was four, five and six. We absolutely wanted him to be a four, five and six-year-old, the way the rest of them are. We wanted him to be naughty, to play, to have an absolutely normal experience.”

At City of London, form tutors are briefed about any celebrity connections in advance. The purpose is to ensure that, as much as possible, teachers make no reference at all to famous parents. At school, children should no longer be judged by the sins of their celebrity fathers.

“The emphasis is on achieving normality, so that all 22 boys in a class have the same experience of school,” Mr Levin says. “Of course, a boy might mention a parent’s film or speech as part of a discussion with a tutor, and the teacher will carry that on. But otherwise teachers are counselled to keep well clear.”

The only occasion when teachers might initiate such conversations would be when the famous parent was being used as an excuse to taunt or bully the child. Boris Berezovsky’s son, for example, was faced with cutting remarks about his father’s questionably gotten gains.

“On a couple of occasions, form tutors have had to step in and speak to boys, when joshing was too personal,” says Mr Levin. “Boys making unfair remarks about acting ability or parents’ other activities. We say, `That’s not relevant. The son has nothing to do with his father. He is a boy here, like any other City of London boy. He has the same rights and benefits that you do’.”

On the whole, however, children tend to be unconcerned by who their classmates’ parents may or may not be: one adult is, to all intents and purposes, much like another. “There are 1,300 teenage boys living here,” agrees Mr Little, of his Eton pupils. “There are an awful lot of adults within the community. No individual is that significant.”

“If Cheryl Cole or Simon Cowell walked into the playground, then children might be interested,” Ms Russen concedes. “If I said, `Barney the dinosaur is coming to school tomorrow’, it would get a real woof of applause. But if I said, `Guess what? Nick Clegg’s son is coming to school tomorrow’, there would be barely an eyebrow raised.”

To a large extent, ignoring the problem will indeed make it go away: refusing to acknowledge the fame of a child’s parents effectively undermines their status. But, while school may be an oasis of media oblivion, headteachers cannot force the wider world to abide by school rules.

On one occasion, for example, a story involving the famous father of a City of London pupil erupted across the pages of national newspapers. As a result, the affected boy was kept off school while the scandal raged. In his absence, his form teacher briefed his classmates, carefully answering any questions that arose. When the boy returned to school, Mr Levin held a meeting with his form tutor, his head of year, his mother and a couple of policemen.

“I think the boy was delighted to return,” Mr Levin says. “He regarded school as a breather, as a respite. He wanted to be back with his mates, playing football, getting involved in debates, doing all the things that boys do. And he was very touched by the support from his mates. They were very, very concerned for him. There was a feeling that, oh my goodness, this is really grim for the chap concerned. Boys are quite tribal: the whole class ranks around one of their own. In this case, it was very positive.”

The boy’s form tutor, meanwhile, engaged him only in the same “How’s it going today?” exchange that he might have had with any other pupil. Indeed, both Mr Levin and Mr Little are keen to point out that the concerns raised by a national newspaper scandal are not entirely dissimilar to those raised by stressful or upsetting incidents in non- celebrity lives.

“In a boarding house, you have adults who live around you,” Mr Little says. “In, I hope, a low-key but effective way, we have a lot of people who are looking out for individual boys.

“The purpose is for the teacher to respond in the best way for an individual child, no matter what the circumstances. When a parent dies, for example, it is likely that the housemaster will make sure the boy’s friends hear about it in the right way. It is the same category and approach.”

Mr Little, like Mr Lyon, takes a hatches-battened policy to media questioning; as a result, the questions very rarely even arise. And this is Mr Lyon’s final rule: no boasting, no surreptitious leaks, no attempt to use a famous parent as an unwitting advert for the school.

“If nobody knows, it has no effect on the school,” he says. “Parents don’t know, unless through word of mouth, through their children. It’s not made into an issue; it’s not spoken about. There has been no change in our admissions numbers. I think the majority of people just don’t know.”

The advantage, of course, is that most celebrity-endorsed schools are likely to be highly successful anyway. With the power to pick and choose, famous parents tend to choose the best. Mr Lyon’s school is already oversubscribed: he has nothing to gain from attracting even more applicants. And so he refuses to allow his school to be used in any publicity campaigns. He will not, for example, launch new Government initiatives from his school hall.

“Yes, I launch new initiatives,” he says. “But nobody can use me as publicity for it. If they did, you would be using your famous parent, whether they were a famous pop star, actor, politician. And that is wrong. It’s prostitution.

“We are a successful school, a very popular school. I have gone through several years now without any issues.” He pauses. When he speaks again, there is a warning edge to his voice. “I’m not going to have one now.”

Ten commandments

1. Never talk to the press. “No comment” is the right comment.

2. Silence is golden. Do not boast about celebrity parents outside school.

3. Remember that anything that attracts public attention for the school - however irrelevant - will inevitably lead to the famous parent’s name being associated with the school.

4. Conduct a security risk assessment to ensure all necessary measures are in place.

5. Remind staff that they should not talk about pupils, famous or otherwise, outside school.

6. At school plays and parents’ evenings, treat celebrity parents as you would any other parent.

7. Teachers should not mention a child’s famous parent. Any references should be initiated by the child.

8. Refuse to concede to famous parents’ demands. Their children should not be given any additional security or protection.

9. If scandal breaks, discuss it with the child and famous parent, as well as - separately - the child’s classmates. They are likely to be supportive.

10. Treat the children of famous parents as you would any other pupil. Ignore the problem and it will, essentially, go away.

• Original headline: A life less ordinary