Davey Graham was the doyen of British acoustic folk guitarists. His virtuosity and invention inspired a generation of players, such as Bert Jansch, John Renbourn and John Martyn, as well as many outside the folk world, including Paul Simon and Jimmy Page.

His best-known piece was the instrumental Angi, which became the signature tune of every aspiring finger-picking guitarist in the 1960s. A famous maverick who was always two steps ahead of the pack, he eclectically mixed traditional English folk songs with blues and jazz and travelled to North Africa and the Near East, where he absorbed Arabic and other influences, adding them to his guitar repertoire long before anyone had invented the term “world music”.

Although he was so strongly influential, his refusal to stick to one style contributed to his failure to enjoy much mainstream success, and in the 1970s he disappeared from view. Rather like Peter Green, the talented but troubled guitarist from Fleetwood Mac, who fell off the radar around the same time, he suffered from personal problems and became “a casualty of too much self-indulgence,” as he put it some years later. Motivated by his own unhappy experiences, he went on to work for various mental health charities and was for some years on the executive council of Mind.

Like Green, he returned to performing later in life, but although his last concerts were nostalgic occasions he never quite recaptured his early virtuosity, and there was something wistful in the way he would tell his audiences, “I’m a bit slower than before.”

David Michael Gordon Graham was born in 1940 in Hinckley, Leicestershire. His Guyanan mother taught him French, and his Scottish father spoke Gaelic to him. He began playing harmonica and piano as a child. Although he never had formal music lessons, he could, he claimed, “remember almost anything that I’d heard”, and by 12 he had graduated to the guitar.

Inspired by the pioneering British folk guitarist Steve Benbow as well as recordings by US acoustic blues performers such as Big Bill Broonzy, he first came to wider attention as a guitarist when in 1959 he was seen playing Cry Me A River on the BBC’s Monitor arts programmes, in a film directed by Ken Russell.

Shortly afterwards he wrote the instrumental Angi, dedicated to his then girlfriend, although there is some controversy over the tune’s origin. In the early 1960s he was part of a coterie of young acoustic guitarists who met at the Gyre and Gimble coffee shop in John Adams Street, Charing Cross, to play together and swap tunes. One of them, Sydney Katzenell, has suggested that Graham developed and polished Angi from one of his pieces, although the claim has never been verified. Whatever the truth, such borrowing and adaptation have long been accepted practice in the folk world, and Graham — billed at the time as Davie rather than Davey which he adopted later — was the first to record the tune in early 1962 on the EP 3/4 AD, recorded with Alexis Korner.

The tune was swiftly taken up by almost every other aspiring folk guitarist in Britain. Bert Jansch recorded it on his 1965 debut album, and Paul Simon, who was performing on the London folk club scene at the time, recorded it as Angi on Simon and Garfunkel’s 1965 album The Sounds of Silence.

Graham went on to record six full-length albums for Decca during the 1960s, exploring a wide range of styles that included jazz and blues as well as Indian ragas and European and Middle Eastern sounds. The most influential was probably Folk, Blues and Beyond (1964) but Folk Roots, New Routes, recorded a year later with the English folk singer Shirley Collins, is also regarded as a classic.

His career was not helped by his tendency to disappear for months at a time on his travels abroad, from which he brought back new musical ideas, including the modal DADGAD guitar tuning, since much copied but which he is credited with inventing.

His restless travelling, however, also gave him a reputation for unreliability and, coupled with his determination to pursue a maverick path, he enjoyed less commercial success than many of the folk guitarists he influenced and who regarded him as the maestro.

By the time of the fascinating but undeniably eccentric 1969 album The Hat, it was becoming increasingly clear that not all was quite right in Graham’s world. Many of his troubles were undoubtedly related to his drug use, and he experimented with cocaine, LSD and opium. In an interview many years later he attempted to explain why his life went off the rails in the late 1960s.

“I felt that the guitar playing was getting out of hand. There were too many tragedies happening in the world to ignore them,” he said. “I spent time doing charity work, finding something more interesting than just Davey Graham to be getting on with. There has been too much publicity for things I did in the Sixties.”

A handful of sporadic recordings appeared during the 1970s but years of obscurity and hard times followed. Interest in his music was revived by a BBC radio documentary about him in 2005 entitled Whatever Happened to Davy Graham. He returned to the stage and his early recordings were reissued.

In 2006 he appeared in the BBC Four documentary film, Folk Britannia. His most recent album, Broken Biscuits (2007), recorded with the singer-songwriter Mark Pavey, was a typically eclectic collection.

Davey Graham, folk guitarist, was born on November 22, 1940. He died of cancer on December 15, 2008, aged 68