As one of three principal tenors, Evans was a founding member in 1946 of what was then the Covent Garden Opera Company (now the Royal Opera). During his nearly 30-year career, he sang around 45 roles at Covent Garden, under conductors including Thomas Beecham, John Barbirolli and Rudolf Kempe.
Those roles included Steva in the first British stage performance of Jenufa, Zinovy in the British premiere of Katerina Ismailova (the 1960s Soviet revision of Lady Macbeth of Mtsensk), the Interpreter and a Celestial Messenger in the premiere of Vaughan Williams's Pilgrim's Progress, Andres in the first Covent Garden Wozzeck, and Captain Davidson in Richard Rodney Bennett's Victory.
Evans became one of the first postwar British tenors to sing abroad when Erich Kleiber took him to perform in Wagner's Ring with the Rome Opera. Later he returned to Rome to continue his studies with Luigi Ricci.
Born in Cwrt Newydd, Wales, in 1912, the youngest of 13 children, Edgar heard the voice of Enrico Caruso over the radio at the age of eight and decided he wanted to be a singer, although his father, a farmer, hoped he would become a banker or an architect.
Edgar had no formal musical training as a boy and was always being told that he sang too loudly, according to a biography on the BBC Wales website. Only his mother encouraged him to sing, saying that his voice had a "ring" to it unlike those of the rest of his family or anyone else in his hometown.
The opportunity to sing professionally came when he was heard singing in a pub while on a rugby trip to London in 1935. He was recommended to Dawson Freer, a professor at the Royal College of Music, with whom he began to study one week later. Freer reportedly began by telling him that he sang too loudly.
When his funds ran low, Edgar worked as a milkman in South London, getting up at 5 a.m. every day. In 1937, eighteen months after meeting Freer, Edgar was offered a contract to sing as a chorister with the Sadler's Wells Opera Company on a salary of Ô£3 a week.
Edgar then auditioned for the newly-formed Covent Garden Opera Company and was offered a contract in 1946. His first roles were as the bird god and lover in Purcell's Faerie Queene in a cast that included Michael Hordern, Constance Shacklock, Margot Fonteyn and Moira Shearer.
After he retired from Covent Garden, Evans joined the Royal College of Music, where he taught vocal technique for ten years.