Leeming retired from television in 1987 and has managed to eke out a modest living doing corporate work and raising money for her pet project . . . a cheetah conservation sanctuary in South Africa. She is hoping to use the 38,000 she is estimated to earn from the programme to help her to move abroad . . . a move which seems ever wiser by the day as 'antics' on the programme, which include arguing with some other woman and saying she would "pose for Playboy" . . . have made her almost untenably unpopular at home. This week the show's viewers have voted for her to jump out of an aeroplane and eat a selection of live insects and raw kangaroo privates while the media have been running headlines about "Screaming Leeming", dredging up details of her failed marriages and getting bitchy quotes from ex-colleagues who call her "difficult and quite intense".

And yet her son admits that his mother had little idea of what she was letting herself in for in agreeing to be marooned in a jungle camp with a group of strangers and then being forced to endure humiliating and physically difficult "bush tucker" challenges in order to earn food. After refusing to eat a kangaroo anus on Wednesday night, Leeming tellingly confessed to her fellow campers that "my agent told me this was all made up . . . that it was all a game". Later on in the programme, we saw her argue with one of her fellow campers and then break down sobbing because she had been driven to use the 'f ' word on television. A rather touching, old-fashioned sentiment which revealed little more than the fact that Jan Leeming is of a certain age and has a slightly offputting personality. If we all look hard enough we will find a Jan Leeming on our Christmas card list . . . probably in our extended family.

The humiliation of celebrities for our amazement and amusement has become standard television. While shows like Strictly Come Dancing, Cirque Celeb and The Games give our new demigods the opportunity to fall or shine on new talents, Celebrity Big Brother, Celebrity Wife Swap and most markedly this latest series of I'm A Celebrity Get Me Out Of Here imprison them into an appalling situation, then throw rocks at them while we watch. Is it really any more than just our version of a public flogging, the medieval ritual of ridiculing people by putting them in stocks and hurling rotten fruit into their unmoveable faces?

These misguided celebrities often cite, "I wanted the world to see the real me" as a reason they sign up for these programmes. And the "real" them often turns out to be rather less attractive than they had banked on.

Ex Big Brother contestant Anna Nolan acknowledges that when she entered the Big Brother house in 1999, "it was an interesting social experiment. Now reality television is a social phenomenon.

I think celebrity television of this kind is interesting because the celebrities don't fully understand what it is they are signing up for.

In reality television like Big Brother . . . the contestants are usually ordinary people who have been avid watchers of this type of TV.

While they aspire to be on it, they possibly have a better idea of what is involved than the celebrities . . .

who perhaps view themselves more as an entertainer."

Nolan has managed to use her Big Brother celebrity to carve out a niche for herself as a popular television journalist and presenter. Her experience in the world of media has given her a greater insight into the world of "fame".

"I think that a lot of the celebrities involved are used to having their egos massaged . . . and they don't get that on these types of programmes. They can easily come across as self-centred divas and while they often go in hoping to be exposed as the lovely, decent human beings that they may be in the 'outside' world . . . they are walking into a trap where all of their bad points are going to be highlighted and they will be seen at their very worst."

You often see celebrities describe these programmes as a "game". In fact the sport is in the watching . . . not in the playing. It is car-crash television disguised as a game.

Frenzy for tittle-tattle We have turned celebrities into our modern-day gods . . . we need them to feed our frenzy for magazine tittle-tattle, it is their lives that entertain us more than their talents. Modern celebrity no longer requires much more than a willingness to live in the public eye. Celebrities . . . especially minor and only moderately successful ones . . . need public attention, to be looked at, adored, seen, loved by an audience. That's why they do what they do. They want to entertain us and they want us to love them for it. Yet surely the very nature of seeking out celebrity and fame suggests a weakness in the character . . . a vulnerability; a desire to be liked. For generations our celebrities have been protected and cosseted and revered as repayment for exposing themselves to us through their art.

Now we are asking them to expose their personalities for our entertainment. We punish them for the success we gave them by making them show us how human they are so we can then laugh at them and prod them with sticks.

"I can't watch I'm A Celebrity, " says Anna Nolan. "I don't get any pleasure out of it. Actually, it reminds me of Iain Banks' novel The Wasp Factory . . . about the child who was impossibly cruel to animals. It's a childlike cruelty . . .

pulling their wings off and watching them squirm . . . it doesn't say anything nice about humanity that we find this entertaining."

You can argue that they are not helpless animals . . . that these people are there through choice.

Although you could also argue that celebrities' need for attention acts as a kind of diminished responsibility: a handicap. That their delicate egos make them vulnerable to bullying.

Germaine Greer cited this as the reason she left Celebrity Big Brother in 2005. She said "superior" bullying tactics, like making housemates cold and hungry, could encourage playground bullying.

She also condemned the "complete irresponsibility" of adding fellow contestant Brigitte Nielsen's former mother-in-law Jackie Stallone to the house.

Nielsen had panicked that if she reacted badly it could harm her access to her children, Greer said.

The feminist writer and broadcaster said Big Brother had behaved "like a child rather than a parent" by taunting contestant John McCririck after denying him a cola drink.

"I thought it was actually demonstrating the role of taunting in the playground and there are so many children whose lives have actually been destroyed by this type of behaviour, " Greer said.

Bullying theory The way that the contestants are chosen bears her bullying theory out. Strong characters do emerge . . . but by default. Carol Thatcher, Janet Street Porter and Jordan were three women who more than rose to the challenges given them in past series of I'm A Celebrity.

But who could have predicted that the plain, plummy-voiced daughter of an ailing and unpopular exBritish prime minister would win, or that a brash buck-toothed commentator or a fake-breasted glamour model would come out looking good. They were chosen because they had the potential to be disliked. We didn't dislike them, in the end, because they proved they were strong characters who amused us and could stand up for themselves. The ones we hate are the whingers, the fearful, the weak. I'm a Celebrity gives us the opportunity to vote them into the humiliation of the bushtucker trial so we can watch them fail and humiliate themselves for our amusement. If they do fail . . . the other celebrities get less to eat . . .

so everybody gets punished. All the contestants get angry, and nauseous . . . this week the young actress Phina Oruche was vomiting having eaten a handful of raw beans. Another woman sobbed uncontrollably because she was missing her two young children.

It's all good clean fun. After all, these people have put themselves in these positions so it's okay to taunt them. It's okay to push them to see how far they will go.

There is little doubt that these programmes are becoming progressively more vicious as our hunger for celebrity humiliation increases. The producers are finding new ways to taunt and terrify the contestants . . . separating the camps into men and women . . .

introducing more dangerous and demeaning games for them.

There has been a lot of vomiting in this current series and complaints of extreme hunger. David Gest, a bloated flamboyant American impresario, has started to look ghoulishly unwell, a fact which the presenters, the clean-cut and relentlessly jolly Ant and Dec, seem to delight in making jokes about. The impression they always give is that the complaints of 'humiliation' are hilarious because these celebrities are there completely of their own free will . . . more fools them . . . and could leave at any time.

Former MTV hostess Julie Brown is suing the US production company that made the ABC version of I'm A Celebrity, Get Me Out Of Here. Brown claims she suffered numerous bites and scarring from leeches, despite being told by the show's staff that the blood-sucking creatures posed no harm. In one of the challenges, Brown claims she had to get inside a tub full of leeches. She seeks $500,000 in damages. In response, the reality TV producer Brady Connolly said not only do contestants sign a stack of legal disclaimers, but participants have to know there's an inherent risk in competing in reality shows.

One can only wonder why more of them don't walk out of these shows, yet when Germaine Greer and John Lydon both, famously, walked out of Big Brother and I'm a Celebrity Get Me Out Of Here the exits were palpably painful for the producers. You could see the dismay and panic in the presenters' faces and despite their attempts to weasel PR campaigns suggesting that these characters couldn't stand the pace and were 'weak' for having left, it became clear that there is some psychological force at work keeping the contestants where they are and making it, at best, awkward for them to leave.

Public notoriety But even if the contestants in these celebrity shows are lured there by the promise that their career will be revived, or they get the public notoriety they feel they need . . . even if they are aware of the risks involved . . . does that make it okay? Is it not dehumanising in the same way as pornography is? A girl slightly beyond the age of consent might willingly participate in a porn film but surely the producers of teen-flick porn are morally questionable? Could the same not be said of putting a 64-year-old woman under intense emotional and physical strain, then showing clips of her receiving comforting hugs from fellow contestants and call her "hilarious" and "pathetic" for flirting with younger men on national television?

Jan Leeming may have signed up for a reality television show but she cannot possibly have predicted how cruel the public would become towards her. Any more than newsreader Anne Diamond would have believed the level of "vitriol and prejudice" she experienced for being overweight in Celebrity Big Brother, and then having had weight-loss stomach surgery before she appeared on Celebrity Fit Club.

Celebrity reality contestants are surely like modern-day gladiators, for who could argue that eating a raw kangaroo testicle is today's equivalent of wrestling a lion? We throw them into a ring and watch them suffer for our entertainment, except that unlike the Romans, they are not chosen for this role on their physical strengths but on their emotional weaknesses.

That I'm a Celebrity has created a new breed of hybrid heroes . . . the glamour model who ate live grubs, the camp fashion designer who swam with crocodiles . . . says a lot about the endurance of the human spirit.

That millions of us are entertained by watching them says rather less.

I'M A CELEBRITY WHO GOT OUT OF THERE FORMER 'EastEnders' star Daniella Westbrook was at one stage Britain's most famous drug addict. The young actress who played Sam in the BBC soap opera became known as the "girl with no nose" because of the destruction of her colonna caused by years of cocaine abuse. In May 2003, when she was just over 18 months off cocaine, Westbrook put out feelers to start work again. She was approached by the producers of 'I'm a Celebrity, Get Me Out Of Here' to see if she would appear on the programme, along with, among others, the chef Anthony Worral Thompson, cricketer Phil Tuffnell and the dancer Wayne Sleep.

She had her reservations, but the producers talked her into taking part.

"They told me how it would be a great opportunity for me to turn my life around, that by appearing on the show I could let the public see what I was really like for the first time. If I did this, they argued, people would see me for who I was, not just as a former soap star with addiction problems or the 'girl with no nose'. That sold it to me, " she writes in her autobiography.

Westbrook says she knew she had made the wrong decision as soon as she arrived in the jungle. She cried from the word go, worried that she did not have the sort of support system a recovering addict needs. She told the producers on the 'bush telegraph' that she wanted to opt out. "But they didn't want me to leave. They begged me to stay."

They talked her round and she stayed for nine days. "But all that happened was that I got more and more upset and would cry and cry. And all they did about this was film me, because I guess it made great TV. By day nine I'd had enough. I had to go."

Her experience taught her there was more to life than advancing her showbusiness career.

"I realised while I was there that I no longer cared about my profile. I no longer cared about being famous or living on planet celebrity. I didn't need to do that."