Found - a Keystone file photo from March 9th 1963 of 16 year old novelist Felicity Moxton. Her book Bonsoir Maitresse: a novel (Pavilion Publications, London 1963) was a parody of Francoise Sagan's bestselling 1954 novel Bonjour Tristesse. It is quite rare but looks like this (the design very much like Francoise Sagan's French paperbacks):-
The back of the press photo reads:
Only 16 years old… is the young English writer Felicity Moxton and in a short time her first book will be to get in all book-shops. Felicity is the daughter of a writer in London. Her first book has the title 'Bonsoir Maitresse' and her pseudonym is 'Francine Saigon'. Everybody can see by this title and this name, that Felicity thought to the famous French author Francoise Sagan and her book 'Bonjour Tristesse'. Felicity told a newspaper, that she wanted to make a joke about the books of Francoise Sagan. Let us see, what Felicity had to write!
There are fake reviews at the rear 'Sagan, beware' (Paris Snatch) and 'Proceeds entrancingly from one triviality to another.' (Figarifico). The fictitious former works by Francine Saigon are noted as -Un Certain Sneer, Aimez-vous Hams? and *Marvellous New Ages. The blurb reads:
What is a mistress? How does a mistress begin? How does a mistress end? Exploring this theme, Francine Saigon's new novel tells the story of a young girl's relationship with a father who is more faithful to his old mistress than his successive wives.
Written in the inimitable style which is so familiar to Saigon devotees, 'Bonsoir Maitresse' will linger in the reader's heart long after the covers are closed.
* Les Merveilleux Nuages