He studied history at the University of Cambridge from 1954 to 1957.
He joined the BBC as an assistant film editor in 1961. With the opening of BBC Two in 1964 he began to direct programmes principally about music.
In the early years of BBC2 there was regular coverage of chamber music and Gavin learnt his craft with many studio-based productions. His experience in the cutting room led inevitably to the making of film documentaries.
In 1966 his fascination with contemporary music brought him into contact with the French composer and conductor Pierre Boulez. Over the next 40 years they collaborated on a series of analytical documentaries on the founding fathers of 20th-century music: Schoenberg, Berg, Webern, Bartók, Stravinsky, Ives, Varese, Messiaen and of course Boulez himself.
From the 1970s until the end of the 20th century Gavin specialised in portraits of contemporary composers: Roberto Gerhard, Luciano Berio, Luigi Nono, George Benjamin, Karlheinz Stockhausen, John Adams, Sofia Gubaidulina, Aribert Reimann, Toru Takemitsu, Isang Yun, Harrison Birtwistle, Peter Maxwell Davies, Mark-Anthony Turnage, Oliver Knussen, Hans Werner Henze and many others.
In 1970 Barrie Gavin began to explore folk music with the writer and musician A. L. Lloyd. Together they travelled across the British Isles and visited Romania, Hungary, the United States. The death of A. L. Lloyd in 1984 brought this kind of work to an end.
The vast majority of Gavin’s work has concentrated on music, but he has also produced in 1967 a series on classic film directors. In addition there have been films on literature and the visual arts. Among them: Sir William in search of Xanadu (Award of Montreal Festival of Films on Art, 1984) and Images – A History of Early Photography (Award of New York Festival of Films on Art, 1989).
In 2007 he finished a film, Finding the Music in Croatia, on the composer Nigel Osborne. In 2008 he received an award from International Music Publisher’ Association for Services to Contemporary Music. In 2009 he completed a film Towards and Beyond (Jonathan Harvey), a portrait of the composer. In 2010 he made two short films: A Mind of Winter (George Benjamin) and How Slow the Wind (Toru Takemitsu), using music by these composers. He also started work on a continuing series of archival, unedited interviews, mainly with contemporary composers.
Copies of many of Gavin’s films on contemporary music have been deposited in the archives of the Paul Sacher Foundation in Basel, Switzerland.