In the 1950s, when Gene Kelly was transforming the musical with a series of unforgettable films at MGM, Andre Previn was working for the same studio as an arranger, conductor and composer. The professional collaboration between the two men developed into a close friendship; and when Andre returned to California recently, he went to see Gene at home to reminisce about the golden days of the Hollywood musical, to discuss the chances of its revival, and ask questions. Producer MICHAEL KERR