Margaret Campbell was born and educated in London, and won an art scholarship to train as a photographer. She worked as a photographer in Fleet Street and later turned to reporting.
She had musical training in piano, singing, harmony and composition and sang for many years with Hampstead Choral Society and the Philharmonia Chorus.
In 1961 she turned to musical journalism since when she has contributed regular features on music to The Times, The Times Educational Supplement, The Guardian, The Daily Telegraph and The Birmingham Post. For the last twelve years she has written obituaries of string players and early music performers in The Independent.
She is known internationally for her profiles of string players in The Strad and has contributed to many other musical periodicals including The Musical Times, Musical Opinion, The BBC Music Magazine, Strings (USA), Classical Music and The Consort.
She has made extensive contributions to The New Grove Dictionary of Music (1980 and 2000). She has also contributed chapters to The Cambridge Companion to the Cello (Cambridge University Press, 1999) and provided the entry on Henry Purcell in The Collins Encyclopaedia of Classical Music (2000).
She was awarded a Winston Churchill Memorial Travelling Fellowship in 1971 for researches on her first book Dolmetsch - the Man and his Work, which took her seven years to research and write, and which was published in 1975 by Hamish Hamilton and The University of Washington Press (1975).
Margaret Campbell's Henry Purcell: Glory of His Age (Hutchinson, 1993; OUP paperback, 1995) was voted Biography of the Year by The Yorkshire Post.
Other books include The Great Violinists (Elek/Granada, 1981), The Great Cellists (Victor Gollancz, 1988; Trafalgar USA, 1988) and Married to Music - the authorised biography of Julian Lloyd Webber (Robson, 2001).
From 1974 until 1990 she was Editor of The British Journal of Music Therapy.
She gives regular lectures on musical and literary subjects at universities, music clubs and museums.
Honours include a Fellowship of the Royal Society of Arts (1990) and election as a Freeman of the Worshipful Company of Musicians (2005). In 2006 she was given the Freedom of the City of London.