Possible Clues:

• 'Iolanthe' and 'Candide,' for two
• Works with minimal weight
• Works such as 'H.M.S. Pinafore'
• Works of obscure poetaster
• 'The Mikado' and 'The Merry Widow'
• The Mikado and Iolanthe, say
• Less serious works of kind poet rates poorly