Jimmy Japp is an inspector at the Scotland Yard (the London police). He has worked with Poirot before and thus has a deep and abiding respect for him. Although he and his colleague, Superintendent Summerhaye, want to arrest Alfred Inglethorp right away, Poirot convinces them to hold off. In doing so, Poirot ensures that Alfred can be arrested and tried later on, when there’s more evidence to convict him.