Even the Queen and Blair regret it. So why do we fight to be the stars of reality TV?

The possibility of damaged lives and manipulation in the edit suite still doesn't put participants off. Nicholas Pyke investigates

With her repertoire of strict bedtimes and common-sense routines, Channel 4's Supernanny, Jo Frost, was more than a match for tyrannical toddlers in her charge. Middle-class Britain has watched spellbound as the 34-year-old quelled the tantrums of uncontrollable infants, restoring calm to troubled households. A qualified calm, that is.

With her repertoire of strict bedtimes and common-sense routines, Channel 4's Supernanny, Jo Frost, was more than a match for tyrannical toddlers in her charge. Middle-class Britain has watched spellbound as the 34-year-old quelled the tantrums of uncontrollable infants, restoring calm to troubled households. A qualified calm, that is.

Last week it was the grown-ups' turn to stamp their feet and cry "not fair". Kevin and Amanda Charles stepped back into the limelight to complain that the programme-makers had spiced up the drama in the editing suite. Their children may have been troublesome, but Supernanny portrayed them as monsters with hopeless parents. "They manufactured complete sequences of events that never happened," Mr Charles said. "It was like they had a storyboard and fitted our lives into it."

If the programme itself was compelling, attracting an audience of six million at its peak, last week's epilogue was all too familiar. It is three decades since Britain's first fly-on-the wall documentary, The Family, brought us the Wilkinses of Reading, dirty laundry and all. Generations of rash participants have been protesting ever since, and in growing numbers. However clear the warnings, they seem unable to grasp that the viewers want drama - and that they, the guinea pigs, will be expected to provide it.

They are in good company. The most hardened of politicians and celebrities fall foul of the cameras, despite years of practice. Tony Blair and Alastair Campbell, for example, are said to regret Michael Cockerell's BBC documentary of 2000, The News From Number Ten, a behind-the-scenes look at the relationship between the Prime Minister and his press secretary. One famously off-guard moment made the PM seem wholly in the shadow of his adviser, to the embarrassment of both.

The Queen and Prince Philip were among the earliest victims. Royal Family, broadcast in 1969, was the first programme to show a domestic side to the Windsors. The refusal of the Queen (the copyright holder) to allow sections of the programme to be re-broadcast confirms what many believe: that the family still regards it as a bad mistake.

It is no surprise that the arrival, first, of such docu-soaps as Airport and Driving School, followed by the all-conquering reality show, has been accompanied by a leap in the number of viewers' complaints. Documentaries accounted for 39 per cent of the workload for the Broadcasting Standards Commission in 2002-03 compared with 25.5 per cent the year before. The British Psychological Society has even set up a working group to look at the effects on the participants.

At least the Charles family admits that Supernanny was good for the children. For others the consequences of TV exposure have been damaging or even disastrous. The Wilkins' marriage lasted only three years beyond the series which, they said, had heaped the pressure upon them. Margaret Wilkins commented: "The film-makers are going to exploit you. Things are pieced together in the cutting room."

Bonaparte's restaurant in Silsden, West Yorkshire, was driven to closure after its appearance on Ramsay's Kitchen Nightmares. Sue Ray, the former owner, is considering legal action against chef Gordon Ramsay, Channel 4 and the production company. "They told us they would put us on the map. Instead it put us out of business," she said recently. Again there were complaints of selective editing, but Channel 4 vigorously denies that there was any injustice. Supernanny and Ramsay's Kitchen Nightmares were fair and accurate portrayals of what they found, said a spokeswoman.

Angry participants rarely get anywhere. Ron Copsey from BBC1's Castaway sued the programme-makers and the channel over the way he was presented and won a settlement of £16,000 (with no admission of liability).

What, then, compels ordinary people to sign up for the humiliation of Wife Swap? Some really want to change their lives for the better. But for the most part, it is very straightforward: they like the idea of being on telly. Nick Catliff, managing director of Lion TV, which produced Airport and Airline, detects increasing sophistication among participants. Yet knowledge of the pitfalls has done nothing to diminish the public appetite for appearing on the box. "To the Big Brother generation the idea of appearing on the TV is hugely appealing," he said. "My daughter is 13 and just wants to be famous. So do her friends."

Leanne Klein, executive producer with Wall to Wall TV, which made 1940s House for Channel 4, said it is important for fame-seekers to understand that the final product has to make good viewing. "There's no doubt that as a programme-maker you're looking for the most dramatic moments. You see people at the extreme ends of their behaviour. If they're sitting around doing nothing, you tend not to include that."

More to the point, anyone signing up for a reality show should realise that their comfortable view of themselves could be less than accurate. "Some people are shocked when they see themselves," said Ms Klein. "People are surprised by how they come across because they really don't know."

Even then, it is sometimes left to others to spill the beans. "When we show them a preview, they are happy," said another leading producer. "When we ring them up after the first broadcast, they are delighted. After a couple of days when they've spoken to other people, that's when they start to get concerned."