T he film based on the Fowles' novel "The French Lieutentant's Woman" had to face Foweles device of adopting the convention of the Victorian novel with the narrator who stands above all his characters and presents us with a "realistic interpretation" and a post modern sensibility in which we don't always know what is the true story or what occurs in the minds of the characters. And so Fowles presents us with alternative endings.
How to translate that into film. Here the director borrowed Russell's device of having scenes in which Oliver Reed "plays" Debussy and scenes in which he interacts, as a actor Oliver Reed, with "The Director" and discusses how to play Debussy. This is exactly the device used to portray the fate of Charles and Sarah - in part of the film we see them as characters playing out their lives in Lyme Regus, but at other times we see them as an actor and an actress who must become involved in roles within a film yet at the same them are beginning to become involved in a love affair.
So I would say that a debt is owed to Russell in creating this approach to ambiguity and multiple readings in a film.