Rumpole of the Bailey interest in nineteenth-century anarchists, especially the Russian Peter Kropotkin from whom the title of the play was drawn. The character's name was later changed to Horace Rumpole when it was discovered that there was a real barrister called Horace Rumbold. The title of the play was briefly changed to "Jolly Old Jean Jacques Rousseau" before settling on the less esoteric "Rumpole of the Bailey". Mortimer was keen on Michael Hordern for the role of Rumpole. When Hordern proved unavailable, the part went to Australian-born actor Leo McKern. Mortimer was initially unenthusiastic about McKern's casting but changed his opinion upon seeing
Leo McKern and Disson in Harold Pinter's "Tea Party". He appeared at the Royal Exchange, Manchester in "Uncle Vanya" in 1977 and in "Crime and Punishment" in 1978. McKern's film debut was in "Murder in the Cathedral" (1952). His other more notable film appearances included the science-fiction classics "X the Unknown" (1956), "The Day the Earth Caught Fire" (1961), the World War I drama "King and Country" (1964), "Help!" (1965), the Academy Award-winning adaptation of "A Man for All Seasons" (1966), "The Shoes of the Fisherman" (1968), "Ryan's Daughter" (1970), "Massacre in Rome" (1973), "The Adventure of Sherlock Holmes' Smarter Brother" (1975),