Teela Sanders' research into the sex industry has at times involved her being shoved in brothel broom cupboards while a sex worker met her next client.
"I often interviewed them in their work environment, and they were very clear that their clients shouldn't see me," Dr Sanders said. "I really learnt about their daily routine. There was lots of daytime TV."
One woman who had her own apartment worked between 10am and 3pm, after which she had childcare responsibilities. She told Dr Sanders she could spare only half an hour.
"Over a five-day period, I would get there at 9.30am and interview her while she was getting ready, showering and putting on lingerie."
Dr Sanders, senior lecturer in sociology at the University of Leeds, is a pioneer of research into the "indoor" sex market. The focus of most research has tended to be on the extreme of street prostitution. But Dr Sanders says this is the smallest sex market, and that it is rare for women to move between the two.
"They're different worlds," she said. "On the street, it's complete survival and often the last thing they do to feed a drug habit."
But Dr Sanders, whose publications include Sex Work: A Risky Business and Paying for Pleasure: Men Who Buy Sex, found that most of the women working indoors had a qualification.
"A quarter of them had worked in caring industries, including nursing. Some said that in hospital they did more degrading things and had much less control over their working conditions."
Most had children and many were homeowners caught in a lifestyle trap, admitting that they had now swapped buses for taxis and Asda for Waitrose. The average time spent in the sex industry was nine years, with some working as long as 25, although the majority kept their source of earnings secret.
Dr Sanders, who trained as a social worker after graduating from the University of Birmingham in sociology and social policy, made contact with the workers by shadowing a sexual-health project. She spent months building up a relationship with brothel owners and receptionists before she was able to embark on interviews. And she believes that the Government's current "prohibitionist" attitude to the sex industry will not only block comparable research in future, but also undermine sexual-health projects.
"I doubt I would get that access now because everybody's so scared of police raids. And why would the people looking after the workers want to work with health officials if they think they can get seven years in prison for running a brothel" she said.
"Harriet Harman (the Minister for Women) has got this line that if we stop the demand, the sex industry would then stop. Clearly that's not the case. A market exists because there are two sides, supply and demand."
Dr Sanders believes that the government rhetoric about trafficking shows a lack of understanding of the difference between women who have been kidnapped and coerced, and migrant sex workers who move from one side of the world to the other to boost their earnings.
She recently had a visiting scholarship to the University of Nevada, studying Nevada's regulation of prostitution. She believes this is the safest way to organise the indoor sex market, explaining: "Women are registered, they are very safe, their sexual health is completely taken care of and they are not ripped off financially."
But her scholarship has led to a new research project, investigating the lap-dancing industry, for which she has just won £100,000 from the Economic and Social Research Council.
She noticed that the sybaritic centre of Las Vegas had only 37 lap-dancing bars, while Leeds had 13, a startling comparison.
"A few years ago, there were very few lap-dancing clubs, but now they have become mainstream entertainment, and a work option for many women. How this has happened - economically, culturally and socially - is something that needs unpacking further."
She wants to know how the lap-dancing bars have been accepted as simply another part of the night-time economy, co-existing with other bars and clubs. Her research will range from the licensing authorities and club management to the working conditions of the dancers themselves.
Policy is currently weighted towards communities preventing lap-dancing clubs being opened locally, but Dr Sanders wants to see more attention paid to workers' rights. And she speculates that many lap dancers, who are generally aged 18-21, are debt-ridden students who see this as a palatable form of sex working, with good wages for short working hours. Lap dancing appears to be particularly prevalent in university cities, which have large numbers of young students.
"I think it will be very different from other types of sex industry. It fits into some of the literatures about the sex industry becoming more middle class. You can track it with much wider social changes, including the rise of the night-time economy and more leisure time."
Dr Sanders also wants to find out whether there is less social stigma attached to lap dancing, and whether the dancers tell people what they do, unlike workers in brothels.
"I think there will be mixed results. I think some will be quite upfront and proud of using their body and exploiting the man."