Duet for Flute and Alto Sax (or Clarinet) Perhaps Gilbert and Sullivan's most well-know operetta, The Pirates of Penzance tells the story of Frederic, who was apprenticed to a band of tender-hearted, orphaned pirates. A Sullivan Ballad uses Act 2's hauntingly simple love duet Ah, leave me not to pine alone and desolate as a duet for flute and alto saxophone (or clarinet).