Northern Irish soprano Heather Mary Harper was born in Belfast on 8 May 1930, one of four siblings. She won a scholarship to study piano, viola and cello at Trinity College of Music in London, and won a second scholarship, a year later, to study voice. (Her sister Alice played the cello professionally, in the City of Birmingham Symphony Orchestra, and her brother Ian was a professional horn player in the Royal Opera House Orchestra, the Royal Philharmonic Orchestra and the English Chamber Orchestra.)
Initially a mezzo, Heather Harper sang as a member of the Ambrosian Chorus, the BBC Chorus and the George Mitchell Singers.
She studied with Helen Isepp, retrained as a soprano with Frederick Husler and Yvonne Rodd-Marling, and made her professional debut in 1954 as Lady Macbeth in Verdi's Macbeth at the Oxford University Opera Group. This led to her singing Violetta in 1956 for a TV performance of La traviata, and to further regular TV appearances.
From 1956 until 1975 she was a member of the English Opera Group, appearing as Elsa in Wagner's Lohengrin, the title role in Arabella by Richard Strauss, and in various Benjamin Britten roles, including Ellen Orford in Peter Grimes (which she also recorded), the Governess in The Turn of the Screw and Mrs Coyle in Owen Wingrave. She appeared at the Aldeburgh Festival, in Amsterdam, at the Bayreuth Festival, Carnegie Hall, Covent Garden, Glyndebourne, New York Metropolitan Opera, the Royal Festival Hall, San Francisco Opera, Teatro Colón and in Toronto.
She also had a concert career, which began spectacularly in 1962, becoming known internationally when she substituted for Galina Vishnevskaya at only ten days' notice in the first performance of Britten's War Requiem, later recording the work for Chandos, a recording which won a Grammy Award for best opera recording in 1973. She won another Grammy award in 1979 for the best classical vocal soloist performance with her recording of songs by Maurice Ravel.
She was the soprano soloist in the Delius Requiem, making the first recording of the work, and performing it in Liverpool and London. She gave the first performance of the song cycle Next Year in Jerusalem by Malcolm Williamson at the 1985 Belfast Last Night of the Proms. In 1957 she sang in performances of sacred music by Michel Richard Delalande, recorded on LP, and she appeared on recordings of Mahler's Symphony No 8, Die Frau ohne Schatten by Richard Strauss and Britten's Our Hunting Fathers.
Heather Harper sang in 1994 performances of Berg's Altenberg Lieder and Vaughan Williams' Serenade to Music at the Henry Wood Proms in London, and subsequently retired from singing. She died at her home in London on 22 April 2019, aged eighty-eight.