The famous swimming pool orgy sequence set in Paris, France was actually filmed at "The Sanctuary", a private women's health and spa club in Covent Garden, London. It closed in 2014.
When this movie became successful at the box office, Jackie Collins went out and wrote a book sequel to her novel "The Stud", titled "The Bitch". The books were published about a decade apart, in 1969 and 1979. A movie of the sequel, The Bitch (1979), was made pretty much straight away. Whereas the first movie had taken almost a decade to get made from the time the novel was first published, the sequel had no delays in getting filmed at all.
Dame Joan Collins once described this movie as " . . . a rather erotic and sensual story, but sophisticated, like Shampoo (1975) or Alfie (1966). Ever since I read the book, I have wanted to play Fontaine. She's the arch-bitch goddess, but there's another dimension. There's a lot of sadness there, and a lot of pain."