Which Gilbert and Sullivan operetta is sub-titled The Slave of Duty?
The Pirates of Penzance Pirates of the Penzance Pirates of Penzance Pirates of penzance The Slave of Duty The Pirates of Penzanse The Pirates Of Penzance: Or The Slave Of Duty The Slave Of Duty The Pirates Of Penzance, Or, The Slave Of Duty Pirates Of Penzance The Pirates Of Penzance