Mortimer's most famous creation is a character named Horace Rumpole, a barrister whose specialty is defending those accused of crime in London's redoutable hall of justice, the Old Bailey. Mortimer created Rumpole for "Rumpole of the Bailey", a 1975 episode of Play For Today; Played with gusto by Leo McKern, the character proved popular, and was spun off into a Rumpole of the Bailey television series for Thames Television and a series of books (all written by Mortimer). In September - October 2003, BBC Radio 4 broadcast 4 new 45-minute Rumpole dramatizations by Mortimer starring Timothy West in the title role.