The surprising thing was that everybody seemed to be so surprised. Didn't they watch The West Wing? In episode one Sam Seaborn unwittingly sleeps with a high-class hooker called Laurie. Laurie is paying her way through law school by working as an escort girl on the side. This storyline didn't come out of thin air.

For decades, bright, young, pretty students have been supplementing their income by sleeping with men for money. It's easier than waiting tables, leaves them time and energy for study, and -- as so many of them point out -- they'd rather get paid for sex than give it away to some spotty, ungrateful, teenage boy.

According to Catherine Stephens of the International Union of Sex Workers: "Loads of people who work in the sex industry are academics. Education is a very expensive habit. At a brothel I worked in, I think I was the only one not doing a PhD".

Last week Dr Brooke Magnanti, a scientist at the Bristol Initiative for Research of Child Health, revealed that she was, in fact, the celebrated ex-hooker, and best-selling author Belle De Jour. The TV drama Secret Diary of a Call Girl was based on her experiences as a prostitute.

The morality police have since been out in force, appalled at Magnanti's claim that she worked as a call girl because she liked the sex, the money and the fact that it gave her time to study.

It would have been so much easier if she had been a heroin addict from a deprived background. Or if, as so many of her critics originally asserted, a fake: a clever young man perhaps, exploiting that old chestnut, the myth of the happy hooker, for literary gain. She wrote so well, you see, and she sounded so normal, witty and well-rounded -- she couldn't actually have done all those dreadful sexual acts, could she?

Well, she did. And then went on to finish her PhD. She now carries out essential research into children's cancers -- a storyline that would probably have been too far-fetched even for the producers of Billie Piper's Call Girl series. It's all wrong, you see. Prostitutes are not supposed to have happy endings -- outside Hollywood anyway.

Consequently, much has been made of the fact that Magnanti's father admitted to using and introducing her to prostitutes and that she must have been emotionally traumatised by this. Otherwise why would she -- a pretty, intelligent, middle-class girl -- have chosen to work as a hooker?

Even worse, why does she not regret it in a heart-rending emotional expose where she explains how the psychological scars will remain with her for the rest of her life?

How can she sit there smugly, smiling happily at the cameras and insisting that 18 months of selling her body was a rite of passage, her version of a Saturday job?

And yet, for some women, this is the reality of the middle-class sex industry: the world where sex is discreetly traded through escort agencies and personal ads, where women are paid -- not for sex -- but 'for their time' and if anything else occurs well, they're 'consenting adults', aren't they?

Have a look at a leading English ('Royal Girls') escort agency website: its legal disclaimer reads, "The money exchanged between the companion and client are solely for the time and travel expenses associated with the engagement requested by the client."

On its 'casting' page it asks would-be escorts:

"Are you adventurous and open to new experiences?

Do you like travelling around the world?

Do you enjoy spending time in high society and a high level of lifestyle?"

"Yes, yes and yes," answer some young women. And I bet they'll get paid a hell of a lot more than £300 an hour (What Magnanti charged her clients).

What's not said, of course, is that they will have to perform sex acts.

Then again, these young women may complain that if they go on a date with a man and he picks up the tab for dinner he will expect sex in return, at least this way they are getting properly remunerated for their wit and charm.

Is there a difference between them and the girls on the side of the street who perform sex tricks for a pittance or the woman who is kept in a brothel servicing 20, 30 men a day?

Well, yes there is -- I would have thought that was obvious. But there are many people who still insist that all prostitution is equal, that selling sex, whether it be high or low-end is just wrong, plain and simple.

The word 'prostitute' is emotionally laden. We use it as a verb of abuse: He/she 'prostituted' themselves. But morally there is nothing wrong with prostitution if it's an equal exchange between consenting adults.

The problem is that so much of it isn't an equal exchange and the woman is not freely consenting. More often than not prostitution is a sad tale of violence and abuse, of drug addition and misery. Increasingly, women are being trafficked through Europe and forced to work as sex slaves. Rape and torture is common.

But there is a world of difference between a woman who works for a high-class escort agency and a street hooker with a drug habit and a violent pimp. One is in control, the other is not.

Whether we like it or not, there are women, like Magnanti, who actively choose to work as prostitutes.

The money is good and the hours are flexible.

And middle-class prostitution is a growing industry. If you don't believe me type 'female escort' into Google and see how many hits you get. And considering the economic climate, it's set to grow even more as women are forced by financial need to sell their bodies.

Sure, most of them would prefer not to have to do it, they would prefer to have well-paid, interesting, secure jobs; but life is tough and sometimes beggars can't be choosers.

Recently, in the wake of the 'Belle' scandal, I chatted with some friends who have been hit very hard by the recession. Not one had a moral problem with a woman accepting cash for sex if the money was desperately needed. One or two even joked that they may be investigating some escort agency adverts themselves. But we all knew that if push came to shove and one of us had to work as a hooker to make ends meet we wouldn't be telling our friends over a glass of Pinot Grigio.

The reason why? The insanely judgmental and unrealistic view still held by many commentators where sex is involved.

As one journalist wrote on hearing about Magnanti's exploits: "The silly cow. It takes someone so intelligent to be so astoundingly stupid. Like many brilliant scientists, Belle de Jour is several elements short of the full periodic table. In her sense, the vital element missing is a moral sense."

Actually, that's not the case. The reason Magnanti has got up so many people's noses is that the 'vital element' she appears to be missing is not a 'moral sense' but a sense of shame.

She sold sex and didn't say sorry. But then again, why should she?

- CAROL HUNT

Sunday Independent