AS THE person behind the Sheraton Luncheon Club, Richard Finny doesn't actually get much time to eat when playing host to celebrities like Joan Collins and Oliver North. Once every six weeks, up to 450 guests turn up at the Sheraton hotel ballroom, hungry for good fare and the witticisms - or otherwise - of the speakers. Organising the lunches is all part of Mr Finny's job as director of promotions and public relations at the hotel. After seven years of organising lunches in Australia and New Zealand, he joined the Sheraton Hongkong. The local market for the lunches has proved to have a different taste. ''People are more cosmopolitan here,'' said Mr Finny. ''Our biggest draw has been Oliver North, although I expect when the Duchess of York comes next February tickets will be in great demand.'' The food is as important to the Sheraton lunches as the figures, but feeding such a large number of people has its restrictions. ''It's difficult trying to show off what our chefs are capable of,'' said Mr Finny. ''For a start, a lot of people have to be served at once; they can't linger because offices await. And the cross-section of cultures precludes experiment. In addition, with his wife back home in New Zealand, Mr Finny has found himself in charge of the home kitchen and the appetites of two teenage daughters. ''It's a lot of fun. They like nothing better than a dish of nine vegetables all cooked in different ways. I avoid boiling them as I prefer Chinese methods which leave a certain crunch and fresh colour.'' He has also taken on the challenge of teaching them to cook. ''I learned the hard way and I don't want them to repeat my mistakes.'' In addition to cooking the family supper every night, he has guests round once a month. His Sunday lunch menus are invariably simple. The starter would be crudites served with an assortment of creamy dips. An alcoholic mussel dish would follow, with French bread for mopping up the broth. Fresh fruit and cheese would finish the meal, ''as long as people haven't fallen asleep from the effect of the mussels''. MOULES MARINIERE (serves 8-10)6-8 mussels, with shell, per person 3 carrots, finely chopped 3 celery stalks, finely chopped 3 large onions, finely chopped 1 litre dry white wine bouquet garni Garlic to taste 330 ml fresh cream 330 ml cognac or brandy De-beard, scrape and clean mussels. Pour wine into a large saucepan and add vegetables and bouquet garni. Bring to boil. Immediately add mussels. When shells open, remove and keep warm. Sieve wine and return mixture to pan. Boil rapidly to reduce by half. Add cream and cognac, stirring constantly. Place mussels in tureen and pour over sauce. Serve with crusty bread.