It's not just men who pay prostitutes to sleep with them. For some women, paying for sex is more convenient than cruising bars and clubs trying to find men.
"They don't want to be found out. They want to do something private - it's their own world, a part of their life that they want to be secret."
Nicole runs a high-class escort agency in the West Midlands, whose clients include women as well as men. Her male escorts host "in-calls" for female clients at a large country cottage, three quarters of a mile away from the nearest town. The exterior gives no clue as to what goes on inside and instead looks more like a French chalet.
Male escorts know that some of their clients aren't single. One says some women don't think paying for sex is cheating, in the same way that having an affair would be.
For women who are attached, the risks of going to a bar or a public place to meet a man are often seen as too high, and so having a discreet hide-away can be crucial.
"They need to be coming to somewhere where they won't be seen by somebody passing who knows them or a neighbour," Nicole says.
When Catarina took the decision to see an escort, she was petrified.
"I didn't think I'd ever want to see an escort. I always thought it was other people who did that kind of thing - not somebody like myself."
But she is just one of an unknown number of women in the UK who are willing to pay for sex. Born with a disability, sex had always been painful and uncomfortable for Catarina. Her ex-boyfriends had made her feel guilty about not being able to enjoy sex, and left her confidence at rock bottom.
Andrew changed that. After just one session, Catarina says she felt "high as a kite".
"I was able to have sex that was completely pain-free. My self-esteem grew. My confidence grew. If it wasn't for Andrew I wouldn't be where I am today. I wouldn't be as confident as I am, as sexually aware as I am. I think I grew up as well."
It's not just women who have a disability or partners at home that are choosing to pay for sex, rather than cruising night clubs or bars for male company.
Catarina's escort, Andrew Rosetta, has written a book about his 10-year career called Whatever She Wants and he says women come to him for the chance to be selfish.
Sitting in his plush flat in London's West End, which he owns outright thanks to his sex work, he recalls a solicitor who used to be a regular client.
"She's very articulate, bright - she's a partner in her firm. But after session three she told me this guilty secret: that she'd really like to take advantage of Superman.
"I would arrive at her house in a suit. I'd go along in glasses; underneath my suit is a Superman outfit and we would go through this role-play.
"She would at one point bring out a green rock on a chain which was kryptonite - that makes Superman begin to lose his power. And of course when Superman loses his power, he's available to be taken advantage of."
Male escorts say women choose to pay for sex for all types of reasons - to gain sexual confidence, to experiment and some are busy business women who just don't have the time to meet men.
Daniel has been working part-time as an escort in London for the last year, lured by the prospect of making some extra cash in the economic downturn. He was educated at one of the city's best private schools, and like Andrew is highly articulate.
"It's no more seedy than somebody going out to a bar, getting a bit drunk and then ending up going home with a complete stranger. What's the difference? With what I do, you know what you're getting, there's no illusion. You pay your money. You get what you get. You meet some guy at the bar, you don't know what you get - he could be anyone."
So how much do these services cost? In London the top straight male escorts charge at least £100 per hour - often more.
But Nicole says that in the West Midlands, the men on her books offer rates of around £60 because of a shortage of work at the moment. In this economic climate, times are tough, even for the male escort.
Good money if you can get it.