In the novel A Caribbean Mystery, Miss Joan Prescott is an elderly woman who enjoys gossiping. She has come on holiday with her brother, Jeremy, to the island of St Honoré and while there, made the acquaintance of Miss Marple.
Joan Prescott is featured again in the novel Nemesis. There, Miss Marple receives a posthumous commission from a fellow acquaintance from St Honoré, the wealthy businessman Jason Rafiel. He wanted Miss Marple to invesitgate an unspecified injustice. Miss Marple thought the best way to begin was to gather some background from his former secretary Esther Walters. So Miss Marple wrote to Joan Prescott to ask if she had Esther's latest address. Miss Prescott replied quickly giving the details and adding that she had since been married and was now Mrs Anderson.