Husband and wife Ludwig and Malvina Schnorr von Carolsfeld created the original roles in the 1865 Munich premiere of Wagner’s opera. After Ludwig’s sudden death only six weeks later Malvina never sang again. Photograph: AlamyNina Stemme as Isolde and Stephen Gould as Tristan the Royal Opera House’s current revival of Christof Loy’s 2009 staging. Photograph: Tristram Kenton/Tristram KentonGwyneth Jones (left), as Isolde, with Simon Estes (right) as Tristan in a 1980 staging in San Francisco.Photograph: Ira Nowinski/Ira Nowinski/CORBIS