Peter Coleman-Wright played Demetrius in which opera whose music was by Benjamin Britten?  
Peter Coleman-Wright:  Subsequently, he sang Sid in "Albert Herring" and Demetrius in "A Midsummer Night's Dream" and Pizzaro in "Fidelio". A Midsummer Night's Dream (opera):  64, is an opera with music by Benjamin Britten and set to a libretto adapted by the composer and Peter Pears from William Shakespeare's play, "A Midsummer Night's Dream".
A Midsummer Night's Dream