FROM her designer dresses to her black lacquer dining suite, new Housing Authority chairman Rosanna Wong Yick-ming is Mid-Levels through and through. It was where she grew up, where she started her family, and now, having split from her husband, it is where she raises her two children in a smart Conduit Road apartment. For an estimated $4 million, Ms Wong bought a three-bedroom, two-bathroom, 1,250-sq-ft flat with a balcony and a splendid view. It comes complete with swimming pool, children's playground and barbecue pits. The property is very much in keeping with the style to which she is accustomed. Before that, she spent years in the doctors' quarters of Queen Mary Hospital in Pokfulam. It was a flat of at least 1,500-sq-ft for which her ex-husband, a doctor, paid a nominal sum as rent. Perhaps the one flat she could call cramped was the one on Lyttelton Road where she grew up. The 1,200-sq-ft apartment was home to eight people - including her secondary school teacher mother, businessman father, and four sisters and one brother. ''It is a fact of life,'' she said of her Mid-Levels residential status. ''But one cannot draw the conclusion that because of this I am unable to understand the conditions in public housing estates.'' Ms Wong has spent the week since her appointment was announced strongly defending her middle-class background, maintaining it does not make it impossible for her to relate to public housing tenants, many of whom spend a lifetime in tiny flats sharing bathrooms and bedrooms with, sometimes, three generations of a family. ''Are you suggesting being the chairman of the Housing Authority [that] you must live in the public housing estates?'' she asks defensively. ''Are you suggesting that only those who live in public houses can understand how the public housing tenants live? ''I think there is a strong point in that but it does not mean it is absolutely correct. ''The only thing that matters is for the person to have an understanding heart and mind . . . I have the heart,'' Ms Wong said. No one doubts she does. But she will need more than that. Many of those who criticised her appointment missed one crucial point - the nature of Hongkong's public housing estates is changing. Yes, many tenants are indeed poor. But many are nudging the sandwich classes. Some have even higher incomes. Making them share a more equitable financial burden - or even persuading them it is time to move on and out into the private sector to free up homes for the genuinely needy - is an important part of the Housing Authority's new challenge for the '90s. And with two debacles behind it - the attempts to sell tenants flats they did not want to buy, and the double-rent policy - it is no challenge for the faint hearted. Ms Wong maintains her training as a social worker, and her experience working with the poor, the needy and the handicapped will help her. ''I have a lot of experience working with young people, and a lot of them live in public housing estates. This is not the first time I have worked with people living in these estates. This is not something entirely new to me,'' she said. Ms Wong, 41, is an executive director of the Hongkong Federation of Youth Groups and had worked mainly in the youth service sector since graduating in Social Sciences from the Hongkong University in 1975. While she was a student at St Stephen's Girls' College on Lyttelton Road, she was drawn to voluntary work that brought her to slums such as the Kowloon Walled City. ''It was my mother who influenced me a lot. She was a very good teacher. It was her who introduced me to voluntary work . . . when I went to the University of Hongkong, my mind was made up on becoming a social worker,'' she said. Ms Wong also thinks it logical that she lives in Mid-Levels. ''I could not pick where I lived when I was young. But my mother taught at St Stephen's, my sisters went to St Stephen's. It is also where my university is. ''I pick Conduit Road now because two of my sisters live on the same road . . . I come from a close-knit family.'' On whether the chairmanship of the authority should be given to a person from the grassroots, Ms Wong said: ''Different people have different strengths and weaknesses. ''If somebody comes from the grassroots who is willing to do the job and if the Governor thinks he is suitable, by all means. ''But the fact that I live on the Mid-Levels should not form a barrier for me to understand people in public housing estates. ''It may not be as good as somebody who has grown up in a public housing estate. [But] I think the most important thing is if I agree to take up the job, I will try my best with my experience and with my training to help. Nobody is perfect.'' She pleads for the chance to serve the poor. ''It is not that only the poor must serve the poor. The rich and the middle class can also serve the poor. ''A lot of volunteers are very good volunteers who live on the Mid-Levels and who have a heart to serve. This is what makes Hongkong tick. ''It is the rich also caring for the poor that makes Hongkong tick. ''The reason welfare services grow so quickly in Hongkong is not because the Government gives money - it is because we have a lot of volunteers. They come from well-off families who care,'' she said. Ms Wong said after graduation she began as a social worker in west Kowloon in areas such as Tsuen Wan, Kwai Chung, and Kwai Fong. ''By then there were already public housing estates there,'' she said. On whether more grassroots people should be appointed to the Housing Authority, she said she had to wait and see. ''There is always a need to balance the interest in the authority. At present there is such a balance. There are people with different backgrounds, coming from different sectors. There are professionals and also those who have grassroots connections. I treasure those who have these connections,'' she said. While reluctant to set priorities, Ms Wong said she realised residents would like bigger flats, and to see the quality of their housing estates improved. ''These are very natural expectations and demands from residents . . . all these points will have to be taken into consideration. ''I am sure as far as improvement of quality goes, the Housing Authority will continue to embark on schemes . . . ''But remember we still have a long waiting list on public housing . . . we still have a lot of people living in squats and we still have Temporary Housing Areas.'' Her first week was spent reading papers and files, and lunching with Housing Authority members. There is evidently a long way to go before she can set priorities.