'Simpson's symphonies... remain one of the best-kept secrets of postwar British music.' The Guardian
Simpson was born in Leamington in central Warwickshire and died in Tralee in County Kerry in the Republic of Ireland. His father, Robert Warren Simpson, was a descendent of Sir James Young Simpson, the Scottish pioneer of anaesthetics; his mother, Helena Hendrika Govaars, was the daughter of Gerrit Govaars, founder of the 'Leger des Heils'. Simpson studied at Westminster School. He was intended for a medical career and studied in London for two years before his determination to be a musician gained the upper hand. A conscientious objector in World War II, he served with an A.R.P. mobile surgical unit during the London Blitz, while taking lessons from Herbert Howells. Howells persuaded him to take the University of Durham Bachelor of Music degree and in 1952 he gained the further degree of Doctor of Music from that university, the submitted work being his First Symphony. After the war Simpson lectured extensively and founded the Exploratory Concerts Society; in 1951 he joined the music staff of the BBC and became one of its best-known and most respected music producers, remaining with the Corporation for nearly three decades. He had married Bessie Fraser in 1946; she died in 1981 and the following year he married Angela Musgrave, a fellow BBC employee and relative of composer Thea Musgrave.
In the latter part of his career as a BBC producer Simpson frequently clashed with the management of the organization. In the 1970s he was one of those - Hans Keller was another - who led a revolt against the proposed decommissioning of five of the eleven BBC orchestras. During the ensuing musicians' strike which caused the cancellation of 1980's BBC Promenade Concerts Simpson chose to disregard BBC staff regulations and discuss the matter with a national newspaper; he then resigned from the Corporation, publicly alleging a 'degeneration of traditional BBC values in the scramble for ratings'. Had he remained silent for a few more months he would have been able to retire with a full pension, but his feeling was that such a course would have compromised his principles. Abominating the ethos of Thatcherite Britain, in 1986 he moved to Ireland, settling on Tralee Bay in Kerry. In 1991 he suffered a severe stroke during an English lecture tour, which caused damage to the thalamus that left him in debilitating pain for the remaining six years of his life.
Simpson's other great passions were astronomy (he was a member of the British Astronomical Association and – unusually for an amateur – was made a Fellow of the Royal Astronomical Society) and pacifism, specifically addressed in the title of his Tenth String Quartet, For Peace. He was awarded many honours, including the Carl Nielsen Gold Medal, 1956 (for his book Carl Nielsen, Symphonist, published 1952), and the Medal of Honor of the Bruckner Society of America, 1962; when offered the CBE, however, he refused it.