In the short story The Case of the Caretaker, Mrs Bella Edge is the wife of the chemist. He father was the tobacconist. In her youth she had been entangled with Harry Laxton. She appears as a character in a manuscript written by Dr Haydock.
Bella is described as having been a "dark, handsome girl", and a "reasonably handsome woman, though she had put on weight, and the lines of her face had coarsened". She has large brown eyes and large white teeth.
Miss Marple later surmises that Harry was probably not attached to Bella anymore, but he might have made her think that he was. He might have done this to get her to help him get a drug with which he could murder his wife.
It is revealed that Bella was questioned by the police, and admitted to having gotten strophanthin for Harry.