The World of Eddie Weary (1990)

Alex Conway is an actor who plays the part of 'Eddie Weary', a sympathetic, down-at-heel, shabby, Northern, working-class private detective, in a TV show. Except Conway is actually a complete idiot in real-life: stuck up, pretentious and selfish, the constant focus of tabloid interest for his bad, usually drunken behaviour. But then he discovers he gets truckloads of mail from fans who think he really is Eddie Weary, asking for his help, so he decides to help them - with the aid of his assistant, Birdie.