From Wikipedia, the free encyclopedia. Margaret Valerie Masterson (born 3 June 1937), is a retired English opera singer, a lecturer and Vice-President of British Youth Opera. After study in Italy, she began to sing opera in Europe. Returning to England, Masterson performed as principal soprano with the D'Oyly Carte Opera Company from 1964 to 1969, becoming popular with audiences and participating in several of the company's recordings, as well as those of Gilbert and Sullivan for All and the BB ...