In 1921 she was invited to appear with the Hallé Orchestra, and she made her first, highly successful, London appearance in 1923.
Widely praised for the purity and clarity of her tone, she was in demand for choral works; apart from the Messiah, she was noted in Joseph Haydn's The Creation, Felix Mendelssohn's Elijah, and Johannes Brahms's German Requiem. In 1933 she became the first British performer to sing in the Hollywood Bowl in California when Arturo Toscanini chose her to sing Brahms's Requiem. Her performances of Gluck's Orpheus (always in English, so not Orfeo ed Euridice) and Charles Gounod's Faust were very popular.
She taught at the Royal College of Music (1955-1957, 1961-1964), Cornell University (1960-1) and the Manchester School of Music (from 1970). She gave a few lessons to Kathleen Ferrier, and often sang with her.
In 1951 she was made a Commander of the Order of the British Empire; in 1978 she was made a Dame Commander of that order.
She said that the best advice she had ever been given was "never sing louder than lovely", and she made that the title of her autobiography.