In the short story Jane in Search of a Job, Detective-Inspector Farrell is a police officer. While investigating the robbery of some valuable pearls from a charity bazaar, he came to the house where Jane Cleveland had been brought to after being kidnapped by the robbery gang. There Farrell happened to eavesdrop on a conversation between Jane and an unnamed man who had followed Jane from the scene of crime. After hearing Jane and the unnamed man exchange their accounts of the events, Farrell became convinced that Jane had been duped and was innocent. He tells them that the police had intel of an american girlbandit being in the country and they had been expecting a coup of a kind. And since they had learned that the grand duchess of Ostravia had just eloped with her chauffeur, it's clear that the one who opened the bazaar was an imposter.
Farrell is not featured in the episode Jane in Search of a Job of The Agatha Christie Hour, a TV film adaptation of the story. There were several policemen in the show but none of them played the role that Farrell did in the original.