text: Peter Grimes is an opera by Benjamin Britten , with a libretto adapted by Montagu Slater from the Peter Grimes section of George Crabbe 's poem The Borough .
simplified: The conductor Sergei Koussevitzky asked Britten to write an opera based on a poem by George Crabbe . The poem , called â The Boroughâ , was about the story of Peter Grimes .