Gilgamesh), Campbell linked up with Stewart again in 1975, this time as part of the original line-up of National Health. Although Campbell initially enjoyed his work with the band (for which he composed several pieces including "Paracelsus", "Agrippa", "Zabaglione" and "Starlight on Seaweed"), within a year he became disheartened by its lack of success. He left the band in June 1976 after a UK tour, a radio session for the BBC and a "disastrous" performance at a one-off French festival (the latter being his final appearance with the group). Although National Health secured a recording contract following his departure, Campbell's compositions would be dropped from the set: recordings of them would not surface until twenty years later on the archive collection "Missing Pieces". World musician (1977–present) Campbell's final gig with National Health resulted in a total discouragement with rock music, and in subsequent years he would abandon the genre altogether, describing it as having "very limited powers of expression... a rather fixed, limited stratum of musical experience, and one that I no longer feel particularly drawn to." In 1977, he dropped his old school nickname of "Mont" in favour of "Dirk" and formed the two-guitar, flute and violin quartet Mozaic, which mostly played "pleasant, undemanding" Campbell pieces at weddings and social events. He also recorded an (ultimately unreleased) tape of other compositions, called Individual Extracts. In 1983, Campbell developed an overwhelming interest in world music and spent most of the next decade-and-a-half mastering a wide variety of wind instruments, harps and lutes from diverse cultures around the world. This led to an ongoing career as a specialist session musician and composer for films, theatre and television, including work with the Royal Shakespeare Company and contributions to The Last King of Scotland, Long Walk to Freedom, Harry Potter and the Goblet of Fire, State of Play, the 2008 revival of Survivors and the 2017 film of The Mummy. He has enjoyed a run of cinema collaborations with his 1970s creative partner David Anderson, including Dreamland Express, In the Time of Angels and Deutsche Post. Campbell released his first solo album, Music from a Round Tower in 1996 (a mixture of authentic traditional instrumentation with MIDI, sampling and sequencing, plus contributions from Dave Stewart). Despite declaring in 2004 that he "personally (had) nothing to say in the western musical language" Campbell followed it up in 2009 with Music from a Walled Garden.