WHEN he began working in Causeway Bay, Leung Kit had thick, black hair. ''Now look,'' challenges the chef, doffing a starched toque, running a hand through his thinning silver-grey strands. Back then, Leung's children were in grammar school. Today, the eldest of four, Yau Man, 42, sits to his father's left. The past week has been bizarre for the chef of the Rainbow Room, a dramatic detour from Leung's usual routine. Rather than writing menus and juggling banquet schedules, he has been shaking hands and brushing away an occasional tear. The 68-year-old native of Guangdong bows to the passing of an era. Yesterday the Lee Gardens Hotel in Causeway Bay closed. And this week has been the swan song for the Rainbow Room where Leung has reigned for more than two decades. On a recent afternoon, after the dim sum baskets were cleared and the customers returned to work, Leung and his son, the sous-chef, talked about the style of Cantonese cooking that made the restaurant famous, the guests who sat in the once-ornate, now-faded room with burnt-sienna and persimmon-coloured furnishings. Each ceiling lantern in its day fetched a six-figure sum. ''I hope Mr Lee will miss my fried rice,'' says Leung, of the owner. ''I hope he will become very hungry.'' His cloud-light, greaseless variety studded with egg, spring onions and strips of beef, was almost a daily staple for the taipan. ''Mr Lee and members of his family would eat here several times a week since I can remember. If Mr Lee gets very hungry, maybe he will open another restaurant.'' Leung, of course, would oblige his former employer. Out of the Rainbow Room's kitchen crew of 24, there are 14 or 15, Leung estimates, that would follow him into such a venture. One who would not is Yau Man. In August, he leaves for Vancouver. The Rainbow Room under Leung nurtured and nourished a galaxy of stars, culinary as well as human. The room where Peking duck, carved table-side, was the most celebrated dish, was where former American Presidents Ford, Carter, Nixon and Reagan dined, as well as sports legends Pele and Muhammad Ali, movie stars Elizabeth Taylor, Leslie Cheung and singers Diana Ross and the Supremes. ''Sir Y. K. Pao used it as his canteen,'' Leung added, smiling, recalling masterpieces such as pan-fried pigeon legs stuffed with minced prawn and crab coral; roast, stuffed boneless duck with minced lamb and sauteed chicken wings with yunnan ham. There are no secrets to the food. ''Simple Cantonese cooking, nothing new or fancy.'' But his tricks and recipes will remain with the chef. Except for the few mastered by Yau Man. What he will miss more than meeting celebrities are faces of his crew and helpers _ the waiters and cooks with whom he shared the 15-hour days. ''I never hated any part of my job.'' But Leung Kit is not optimistic about the future of quality Cantonese cooking in Hongkong. ''Young people have more opportunities today. They don't want to work so hard or have such long hours. Education is changing things. They can make more money elsewhere.'' His future includes travelling to visit his children - Toronto, Melbourne, Vancouver, and Nottingham, England. Since he enjoys good health and vigour, he wants to work, especially if the right opportunity comes along. But for now, his work is dealing with saying good-bye. ''Sitting here reminds me of a poem.'' As Leung recites his version of an old poem, his eyes fill with tears. ''It is about people with white hair, sitting together and talking about the way things were. They have been together so long. They wonder when they will meet again.''