Hercule Poirot

Hercule Poirot was a fictional Belgian detective created by Agatha Christie who first debuted in one of her first six novels. When asked why she made him a Belgian, Christie simply said they make such lovely buns. During her investigations of the murder of Professor Peach at Eddison Manor, she quoted her character when she said "Use the little grey cells," a reference the Tenth Doctor immediately recognised. (DW: The Unicorn and the Wasp)

Although not stated in the episode, The Murder of Roger Ackroyd and Death in the Clouds are both Poirot novels.

Behind the scenes

 * Unlike fictional detectives Sherlock Holmes or Thomas Carnacki, who are crossover characters who appeared in Doctor Who novels, Poirot is not public domain in the UK.
 * The Death of Art has a brief mention of Inspector Anton Jarr's early career in which he worked with a young Belgian police sergeant.
 * Dave Stone created two parody versions of Poirot. BNA: Ship of Fools features Emil Dupont, the self-described greatest detective in all of Nova Belgique. Earlier he created an Andre Dupont, "world famous Euro-Cit amateur sleuth par excellence" for a Detective-Judge Armitage text story.