By the time the latter moved to Sadler's Wells Theatre in 1931 Coates had become its principal mezzo-soprano, and she sang in a wide range of roles, in the Italian, French, German, Russian and other repertoires.
[1][3] Coates began her stage career in 1924, playing one of Titania's fairy attendants in A Midsummer Night's Dream with Lilian Baylis's Old Vic company.
Baylis ran an opera company in tandem with her Shakespeare productions, and Coates sang in the chorus and was soon given small solo roles, beginning with Giovanna in Rigoletto.
[5] She moved up to bigger roles such as Azucena in Il trovatore and the Queen of the Gipsies in The Bohemian Girl, which remained part of her repertoire at Baylis's Sadler's Wells Theatre and later at Covent Garden.
[1] In 1936 Coates made her Covent Garden debut, in Hänsel und Gretel, as an emergency replacement when the singer cast as the children's mother was taken ill; Coates had been singing the same role (in English) at a matinée performance at Sadler's Wells, and hastened into the West End to sing the part for the evening performance at Covent Garden, in which the rest of the cast sang in German.
Coates and her husband joined Joan Cross (soprano), Lawrance Collingwood (conductor) and sixteen others, including an orchestra of five players, taking scaled-down productions throughout Britain, sometimes playing in large cities and sometimes in remote locations where opera had never been seen before.
[1] When Sadler's Wells reopened in June 1945 Coates was a member of the original cast of Britten's Peter Grimes, creating the role of Auntie, the down-to-earth landlady of the village pub.
[16] In the non-Wagnerian repertory she played Marcellina in The Marriage of Figaro to the Susanna of Elisabeth Schwarzkopf,[17] Herodias to Astrid Varnay's Salome,[18] and Klytemnestra in Elektra, conducted by Erich Kleiber in 1953.
She created roles in several world premieres, including Madame Bardeau in Bliss's The Olympians (1949), the Housewife in Britten's Gloriana (1953), and the She-Ancient in Tippett's The Midsummer Marriage (1955).
[27] Her last Covent Garden performance was on 24 June 1967, as the Duchess of Crakentorp in La Fille du régiment with Joan Sutherland and Luciano Pavarotti in the romantic lead roles.
In The Times William Mann called her performance "even more riveting, more finely pointed" than the one that had held Covent Garden audiences "spellbound" nearly twenty years earlier.