Initially coming to attention as a country blues performer, his later work also straddles jazz, Polynesian, ambient, and various experimental and improvisational styles.
[1] The band supported visiting blues musicians including John Lee Hooker, Jimmy Reed, and Sonny Boy Williamson.
He met virtuoso guitarist Derek Hall, and they established a shared residency at the Shades coffee house in Reading, hosting visiting artists such as John Renbourn, Bert Jansch, Davey Graham, Al Stewart and others.
His second album, Do I Know You?, on Pye's subsidiary Dawn label, featured the bass playing of jazz musician Harry Miller, as well as field recordings, and was followed by his 1970 album Trout Steel, featuring a wider range of musicians including Mike Osborne, Alan Skidmore and John Taylor, as well as Harry Miller, Stefan Grossman, and the folk-rock band Heron.
In 1972, he released The Machine Gun Co. with Mike Cooper, a band album on which the other members were Geoff Hawkins (saxophone), Alan Cook (keyboards), Les Calvert (bass) and Tim Richardson (percussion).
[3] In 1977, two of his tracks were included on Stefan Grossman's album Country Blues Guitar Festival which also featured Son House and Jo Ann Kelly.
The same year, he recorded a live album in Berlin with free jazz musicians Dave Holland and Lol Coxhill (credited as "The Johnny Rondo Duo").
Cooper became increasingly influenced by Polynesian slack key guitar styles, and in 1987 recorded an album, Aveklei Uptowns Hawaiians, with French slide guitarist Cyrille Lefebvre and other musicians including Lol Coxhill.
From 1986 to 1996, he performed around Europe (Italy/Germany/Switzerland) with a four piece country blues band called "National Gallery - featuring Mark Makin, Michael Messer and Ed Genis.
[3] His later releases have included Rayon Hula (2004), which incorporates samples of exotica musician Arthur Lyman, White Shadows in the South Seas (2013), and New Globe Notes (2014).