While many women are forced into prostitution by abuse and exploitation, for an increasing number it is a job they choose to make themselves a living.
The biggest surprise when I met Daisy, who has been a prostitute for five years, was how moral she was.
She had been with her boyfriend for two years before she lost her virginity. She is still extremely cautious when embarking on a relationship, never "giving it up too soon", as she put it.
And her priority is providing a stable, respectable home for her school-age daughter.
Somehow I had presumed anyone who sold their body had to be "easy" in their real life. I was wrong.
Daisy impressed me because she did seem to have successfully separated her life as a mother from her work as a call girl.
She had had an ordinary upbringing and her career had been progressing. But five years ago - when the firm she was working for went bust just before Christmas - Daisy found herself struggling to make ends meet.
Too proud to ask for help or borrow money, she answered an 'Escorts Wanted' advert.
She was petrified by her first job. "I was a bag of nerves, I cried my eyes out the whole time I was there," she told me.
But within a couple of days, she had got over her fear. Now she earns between £1,000 and £3,000 a week.
Daisy's plan is to spend two more years building up a cushion of savings and then return to an ordinary job knowing she has a nest-egg should anything go wrong.
None of Daisy's family or friends knows her secret - indeed, "Daisy" is not her real name.
"My parents are respectable people," she said. "It's not that I'm ashamed, it's just they wouldn't understand that I'm providing for my daughter and myself."
Living this double life must be extremely difficult, but I got the feeling Daisy had got it sorted.
She said you needed a certain kind of strength to manage it. "It is what it is. It's a job," she said.
Clearly many other "middle-class" women do manage it too. I spoke about this to Madam Becky, who spent 20 years running brothels and has looked after dozens of working girls.
She told me the highest-earning prostitutes are not necessarily the pretty young girls, but older, well-educated women, often with a background in nursing or another caring profession, who possess the skills to empathise with their clients.
However, Madam Becky has also noticed a trend that she finds quite disturbing. Over recent years she is seeing increasing numbers of "well brought up" girls choosing prostitution not to make a living or pay off debts, but just to finance an extravagant lifestyle.
"They want the £400 handbag and the £300 matching shoes, and they calculate that they can either work for two months to pay for them, or they can sign up as an escort and have what they want by Friday," Becky said.
"They are comfortable with being promiscuous - and they have a bolshy, aggressive attitude to men so they use sex to get what they want. And what they want is shoes, clothes, make-up and nights out."
So the headlines shout about "middle-class hookerettes" but the story is rather more complicated.
Yes, there are many ordinary women who manage to combine a 'respectable' home life with a job as a prostitute, and who have set up a very clear division in their minds between their life and their work.
There also appears to be a new breed of call girls, who are so used to "giving it away" on one-night stands that they find the path into prostitution is a short and easy one.
But whatever motivates women to begin work as prostitutes, what is hard to judge is the damage that this decision may eventually cause them.