

Japp has been depicted in seven novels written by Christie, all featuring Hercule Poirot: In the first novel in which Japp appears, The Mysterious Affair at Styles, he is described as a "ferret-faced man", which is similar to the description of Lestrade as a "ferret-like man" in Doyle's 1891 short story " The Boscombe Valley Mystery".

Christie even modelled Japp after the "ferret-like" qualities of Lestrade. Inspector Japp was inspired by the fictional police detective Inspector Lestrade from the Sherlock Holmes stories by Arthur Conan Doyle. Inspector James Japp (later Chief Inspector Japp) is a fictional character who appears in several of Agatha Christie's novels featuring Hercule Poirot. Philip Jackson as Japp in Agatha Christie's Poirot
