Mrs. Ariadne Oliver, who appears as a character in this episode, was Agatha Christie's alter ego. She was a celebrated detective novelist and the creator of the famous Finnish detective Sven Hjerson. When she worked for Mr. Parker Pyne, she had already authored "forty-six successful works of fiction, all best sellers in England and America, and freely translated into French, German, Italian, Hungarian, Finnish, Japanese and Abyssinian."
She was addicted to apples, and they were her trademark until Joyce Reynolds was drowned in an apple-bobbing bucket in "Halloween Party". In "Cards On The Table", she was one of the four sleuths invited to Mr. Shaitana's bridge party, where she formed an association with Hercule Poirot which spanned six novels. She was "handsome in a rather untidy fashion, with fine eyes, substantial shoulders, and a large quantity of rebellious grey hair with which she was continually experimenting." She was a "hot-headed feminist" who often voiced the opinion that a woman should be the head of Scotland Yard because of the female power of intuition. On the whole, she thought that life was "badly constructed" and said that she "could invent a better murder any day than anything real." Just as Christie tired of Poirot, Mrs. Oliver soon detested Sven Hjerson: "If I ever met that bony, gangling vegetable eating Finn in real life, I'd do a better murder than any I've ever invented."
One of her novels was entitled "The Body In The Library".
Wally, the golden cocker spaniel who appears in this episode, was William Gaunt's own dog, who had earlier appeared with him in 'Nobody's House'
Adapted from a short story in 'Parker Pyne Investigates' by Agatha Christie.