'I doubt that people have to live a heterosexual, monogamous life to find the ultimate goal of happiness,' says Lee. 'That ideology is a suppression of humanity. So why can't society accept people who aren't like them? Why can't it accept a profession that has been around for so long?'

Of all the profession's forms - escort services, massage parlours, karaoke lounges - Lee sought out sex workers on the street, whom she says are 'perhaps the most stigmatised of all'.

She says she was 'very nervous' the first time she visited Shamshuipo. On Un Chau Street, Lee approached a sex worker and paid her $250 just to talk. Lee repeated this gesture with nine other women and in 18 months of field work went on to lend them emotional support and develop 'varying levels of friendship'.

Sex worker Wong Lok-yan (not her real name) is typical of Lee's 10 subjects, all Hong Kong women in their 20s to 40s. Wong, 28, lived near work - commuting would have eaten up too much of the money that she used to feed her six-year-old boy and her heroin addiction. Eight of Lee's 10 subjects were addicts and half were single mothers with one or two children.

Wong's habit of shooting up before work was akin to office workers' morning-coffee ritual, Lee says, 'not only as a pressure release but because they know they're unlikely to quit the profession and they need a good reason to stay in'. She adds: 'Other than supporting kids, drugs are the next best reason. When you take drugs you give up control, and then the rationalisation is that things are out of your hands; it's not your conscious decision to stay in the profession.'

Lee says Wong would service up to 10 men in a typical eight-hour evening shift; the sex worker's low-income customers would range in age, from boys exploring their sexuality to old men. She would earn $250 a trick.

Some days, Wong did little or no business and, if she failed to make money for heroin, she visited Shekkipmei methadone clinic. 'You take heroin when you have the money, go to the clinic when you have none,' Wong told Lee.

Wise to the practice, triad loansharks hang around the clinic and offer the women the real thing. 'The clinic is one of the compelling forces that keeps the women working here rather than elsewhere,' says Lee. Their drug addictions also often kept them in a spiral of debt with the triads.

Lee realised, however, that the two major forces on the street, the triads and the police, both exploited the women in a similar fashion. Police would chase away customers although prostitution - if practised by the rules - is not illegal. 'Their message was the same: you have to pay to work here,' she says. Posing as customers, police officers would often entrap the women and slap them with court fines ranging from a few hundred to a few thousand dollars, depending on whether it was a repeat offence, Lee says.

'One day on the street some policemen mistook me for a prostitute and started yelling at me. When I told them I was with Chinese University they were very embarrassed,' she says.

Lee found herself accompanying the prostitutes to the police station and courtroom, lending emotional and financial support. She remembers riding a bus back to her Tuen Mun home one night when she received a call on her mobile phone that one of the women had just been arrested. 'I had to take a return bus and help her,' Lee says, who went on to give this particular prostitute nearly $4,000 in bail money over two years.

Over time, Lee's identity shifted from 'researcher to a certain kind of friend', and her thesis kept growing. 'Every week I dreaded seeing her because she would have another 80 pages for me,' jokes Gordon Matthews, a department of anthropology associate professor.

Just as she was completing her degree in 1999, Lee finally revealed to her parents just what she had been studying. 'They weren't too happy and thought me daring.' That was when she suffered her breakdown, 'partly related to the research and partly related to the [new] way I saw the world'.

Lee says she was exhausted from struggling to understand her subjects from a different social class perspective, from the emotional investment, and basically from spending so much time with the prostitutes.

'It changed me,' she says. 'I look at things with greater perspective and I have a greater respect for all people.'

Lee now lectures part-time at Lingnan College in Tuen Mun and has found that the social stigma that shrouds her former subjects has also tainted her. She refuses to disclose which department she works in and says: 'Some people here are not happy with what

I'm doing.

'During my research I always thought I'd maybe end up doing something like this,' she says.

Unlike a handful of other non-government organisations that incorporate a prophylactic approach - educating women on Aids and intravenous drug use, and seeking to deter them from a life of prostitution - Zi Teng largely chooses to focus on changing society's discriminatory view of the profession.

For example, Zi Teng publishes two news letters each month, one is a forum for sex workers to share their work experiences, and the other is for public consumption, which sets out to emphasise the 'normal' aspects of sex workers' lives, says spokesperson May Chan Shuk-yuen, like their experiences with motherhood.

Financial support for Zi Teng, a name that refers to a type of vine known for its resiliency, have also been hard to come by. Chan says they offer tips to the women on how to increase their market share or further develop their business.

'We've recommended that they should sometimes change their flat,' says Chan. 'Their clients may feel bored if they are always frequenting the same place.'

Says director Yim Yuet-lin: 'If we rephrased our aim as helping prostitutes to leave the business, I am sure we wouldn't run into any problems seeking sponsorship.'

Lee is no longer in contact with her 10 original subjects though she heard through the grapevine that one died in an apartment fire last year. 'I still feel bad about that. I thought she was one of the strongest of the 10 who accepted who she was and carried herself with dignity.'

At Zi Teng, Lee is working with another group of sex workers and encouraging them to unionise and become a lobbying force for political and social change, but she knows it's an uphill battle.

Says Lee: 'We're working for conscious-raising, for the women to feel good about their job and to change their work environment.' In part by changing policemen's attitudes, with whom Zi Teng schedules face-to-face meetings. 'Social recognition is our ultimate goal,' she says.

Stressing that she speaks from insights gained from her research, and not on behalf of Zi Teng, she says, 'How can society open up to the voices [of prostitutes et al] that it thinks are marginal yet reflect a part of itself? Everyone has desires and feelings they are not willing to reveal. So we cleanse ourselves of evil desires by harbouring disdain for these people. If we can better understand our own desires it will create an ability to listen to other people. Ultimately, I came to conclude that my research was about the right to happiness.'