Information for The Pirates of Penzance at Everyman Theatre, Cheltenham (Opera or Operetta). 'The Pirates of Penzance (or the Slave of Duty)' is probably the most humorous of the Gilbert and Sullivan operettas, with tuneful melodies and well known songs, Poor Wandering One, I Am The Very Model of a Modern Major General, The Sergeant of Police and Policeman's Chorus.