In the novel The Pale Horse, Pamela “Poppy” Stirling is an employee of Flower Studies Ltd.. She is the current girlfriend of David Ardingly.
Mark Easterbrook first met Poppy when she was with David at the Fantasie restaurent. During a discussion of Shakespeare's play Macbeth, the topic drifted to how convenient it was in those times to be able to place an order for a murder when one needed it. Poppy then blurted out her belief that it could still be done but that she thought it would cost a lot of money. In a confused manner, she then added that she thought she meant the Pale Horse organisation. It was something she heard someone mention.
When Mark Easterbrook sought out Poppy at the flower shop, she refused to be drawn further on the subject. She looked very frightened and denied that she had ever mentioned "The Pale Horse".
As Mark sought to investigate the "Pale Horse", he enlisted the help of "Ginger" Corrigan who made better progress with Poppy. "Ginger" was able to elicit important details about the topic using the principle that in "girls-together stuff", what "one girl tells to another girl ... doesn't really count." Poppy told "Ginger" that to engage the "Pale Horse" organisation for a murder, one first needed to settle the business end by seeing one Mr Bradley in Birmingham.
Much later in the book, Mark managed to get more out of Poppy, this time by pretending that he had engaged the organisation but something had gone wrong and he needed to get in touch with them. Poppy suggested that her old school-mate Eileen Brandon might be able to help.
Poppy was described as a very pretty girl, with "a fashionable hairdo, all ends, bits and pieces sticking out at improbable angles on the crown of her head". She had enormous blue eyes and a mouth that was usually half-open. Like the other of David's girlfriends, they were rather silly but he found them "refreshing" provided sampled "in small doses."