He accompanied notable instrumentalists such as Pablo Casals and the child prodigy Josef Hassid, but became better known for his work with singers, among them Elisabeth Schumann, Maggie Teyte and Kathleen Ferrier. He is credited with doing much to raise the status of accompanist from a subservient role to that of an equal artistic partner, in part through his influential 1943 book The Unashamed Accompanist.
Moore also gave lectures and wrote about music, publishing his much-admired memoir Am I Too Loud?: Memoirs of An Accompanist in 1962. He published two other volumes of autobiography: Farewell Recital: Further Memoirs (1978) and Furthermoore (1983).
Moore retired from public performances in 1967, with a farewell concert in which he accompanied three of the singers with whom he was long associated: Dietrich Fischer-Dieskau, Victoria de los Ángeles and Elisabeth Schwarzkopf. This famed concert at London's Royal Festival Hall concluded with Moore playing alone - he chose Schubert's An die Musik. He made his last studio recording in 1975.
In his memoirs Moore wrote that his services were not needed at Benjamin Britten's Aldeburgh Festival, 'as the presiding genius there is the greatest accompanist in the world.' Moore would therefore have been interested that, when in 2006 Gramophone magazine invited eminent present-day accompanists to name their 'professional's professional', the joint winners were Britten and Moore himself.
Moore was appointed a Commander of the Order of the British Empire (CBE) in 1954. He died in Buckinghamshire in 1987.