Wendy loves Soho and has been working there for 20 years running "walk-up" flats, where all the punters have to do to meet a girl is walk up the stairs.

THE PROSTITUTE'S MAID Prostitutes have been around for years and men have always used them and they always will. It's not going to change Wendy, Prostitute's Maid

The girls often call her "Mum". She describes herself as a maid. She works one-on-one alongside a prostitute throughout her shift, greeting the customers, showing them in and out of the flat and writing down the money.

While prostitution is not an offence, operating a brothel is illegal. In the eyes of the law, a brothel is where two or more individuals work together to provide sexual services. But Wendy is unlikely to be arrested and the flat is unlikely to be closed down.

"We've got to be realistic,." explains Chief Superintendent Christopher Bradford of the Metropolitan Police Vice Squad. "If you close a brothel down, it doesn't go away, it just moves... that's a fact of life.

Chief Superintendent Bradford says there are virtually no prostitutes who are doing it because they enjoy it. Instead, he says they are forced into it for economic reasons or by violence.

STREETS OF VICE Sex in the City Tuesday 22 March 2005, 2305GMT, BBC One Smack Alley Tuesday 29 March 2005, 2305BST, BBC One Men for Hire Tuesday 5 April 2005, 2305BST, BBC One Behind Closed Doors Tuesday 12 April 2005, 2305BST, BBC One Sex Lives and Videotape Tuesday 19 April 2005, 2305BST, BBC One Sources of Help and Advice on issues raised in the series

"Prostitutes have been around for years," says Wendy, "and men have always used them and they always will. It's not going to change." She would like to see her work made legal though she fears that might put small operators like herself out of business.

Brothels cannot remove the risk of disease, violence and pregnancy but they can provide working prostitutes with a cleaner, safer and healthier environment than girls on the streets. But they also put them outside the law.

But that could be about to change as the government undertakes the biggest review of laws on prostitution for 50 years.

Britain's Streets of Vice: Behind Closed Doors was repeated on Tuesday, 12 April, 2005 at 2305 GMT on BBC One.