Living in a modest four-room Victorian row house in Camden Town, a slightly seedy district of London. For Leonard Whiting, now 41, playing Romeo at 17 was the bright spot in a film career that quickly faded. ''I was thrust for a long moment into international stardom,'' he says. ''When that happens, people want to see you in that same persona again and again.'' Unhappy with the ''moon in June'' romance roles he was continually offered and with his lukewarm notices in such forgettable 1970s films as Say Hello to Yesterday and Rachel's Man, Whiting turned to the typewriter. His complete -- still unpublished -- works include four novels, two fantasies for children, a full-length gangster musical and (seven drafts later) a sequel to the play that made him famous, Romeo and Juliet 2, in which the lovers come back to life. Whiting's brief, offscreen romance with Hussey during the filming of Romeo and Juliet still stands out in his memory, and he has kept in contact with his onetime costar. ''She still looks wonderful,'' he says, ''only about two years older, whereas I look like Lord Capulet.'' His own 1971 marriage to American model Cathee Dahmen ended after six years and one daughter, now 20. These days, Whiting's Juliet is live-in love Lynn Presser, 40, also his manager. And while there hasn't been much to manage (he has lived mostly on film residuals), things may be looking up. Last year, Whiting did a voice-over for a British cartoon and even starred in Una Nova Primavera, a Brazilian-made art film. His passion, however, is to get backing for his R&J sequel, which he calls ''a cross between Shakespeare's original and Chinatown.'' Whiting is keeping mum about whether the impassioned pair live happily ever after, except to say, ''they have their share of marital troubles.''