Accomplished guitarist of 1960s progressive folk group Pentangle

John Renbourn, who has died aged 70, was a founding member of the 1960s progressive folk group Pentangle.

Best known for his collaborations with fellow guitarist Bert Jansch, who died in 2011, Renbourn helped create a new form of folk music, mixing the traditional with jazz, blues and rock and in some incarnations incorporating Indian instruments. The style is variously known as folk-jazz and folk-baroque.

Renbourn was one of the five original members of Pentangle, along with Jansch, singer Jacqui McShee, bassist Danny Thompson and drummer Terry Cox. At the height of its popularity, the band could command large audiences at venues such as London's Royal Festival Hall, New York's Carnegie Hall, and the Newport Jazz Festival.

Renbourn was born John McCombe in Marylebone, London. His father, Robert, was killed in the second World War and his mother, Dorothy (née Jopling), married Edward Renbourn, a physician, in 1952, when John’s surname was changed by adoption.

The family moved to Surrey, where Renbourn had piano lessons and was introduced to early music. He took grade examinations in classical guitar, which influenced his later folk and blues guitar arrangements.

By the 1980s, he was taking a more analytical approach to his music, wanting to build upon his earlier formal music studies. From 1972 he had been producing books of compositions and guitar tablature, and in 1982 he enrolled on a degree course in composition and orchestration. On one occasion he had to request special permission to re-sit an examination as it clashed with an appearance at Carnegie Hall.

Renbourn was only briefly a member of the re-formed Pentangle in the 1980s, but in 2007 he joined the other original members to receive a lifetime achievement award from Sir David Attenborough. He had recently been touring with one of his early 1960s colleagues, the folk and blues guitarist Wizz Jones. He is survived by three of his four children: Joel and Jessie, from his first marriage, to Judy Hills; and Ben, from his second marriage, to Jo Watson. Their other child, Jake, died in 2014.