His best know work was Crown Matrimonial, which opened in 1972, and has enjoyed numerous revivals around the world.
Update (18th April): There's a nice obituary today by Michael Coveney in The Guardian.
Ryton was a burly man, with a mass of orange, curly hair. He was devoted to his family - he was married to the actor Morar Kennedy (Ludovic's sister) - and was incorrigibly camp in manner. His daughter admits that he had the most appalling taste in clothes, often wearing lots of red with plenty of glitter and frills. For much of the year, he went around looking like a Christmas tree but, like Quentin Crisp, he couldn't care less. He spoke in clipped, aphoristic sentences, a style he carried through in his work. Like Oscar Wilde, he was always "on" in public, and like Nöel Coward, whom he admired inordinately, he was given to a lot of finger-wagging, both on and off stage.