Framed by a long, drooping moustache, Paul Rutherford’s crooked front teeth suggested he might have problems being any kind of brass player, let alone one of the most innovative trombonists in contemporary jazz and freely improvised music. A pioneer of multiphonics, in which by singing a note into the instrument as it is being played the harmonic overtones that are produced give the effect of playing chords, Rutherford worked in an extraordinary variety of settings. On one hand he was a capable and resourceful big band trombonist, playing for the likes of Neil Ardley, Mike Westbrook and Charlie Watts, and on the other he was a pioneer of free jazz playing with the Spontaneous Music Ensemble and his own bands Iskra 1903 and Iskra 1912.

Rutherford was also fervent about the links between free music and left-wing politics, remaining a lifelong communist. “Improvisation and any avant-garde work is progressive,” he said in a recent interview. “Artists can be the greatest gift that any new socialist society can have.”

He helped to organise and appeared in the Moving Left Revues at the Roundhouse in London in 1976 and 1977, on behalf of the Communist Party of Great Britain. This led to the formation of the cooperative Orckestra with members of Mike Westbrook’s band, the alternative rock group Henry Cow and the folk singer Henry Armstrong, which toured in France and Italy. He was also instrumental in arranging the antimonarchist People’s Jubilee at Alexandra Palace, which ran in 1977 concurrently with the Queen’s silver jubilee celebrations.

Paul William Rutherford was a Londoner and began playing the alto saxophone before taking up the trombone at 16. Encouraged by his brother, Dave, he was in various traditional jazz bands in the Greenwich area before joining the RAF as a trombonist in 1958. In the service he studied music formally and met other players with jazz leanings who had also enlisted, such as the saxophonist Trevor Watts and the drummer John Stevens. Rutherford took forward both these aspects of his musical life on leaving the air force. He studied formally at the Guildhall School of Music and Drama (where he later taught) and formed the Spontaneous Music Ensemble with Watts and Stevens, which was the beginning of a distinctly British take on performing free jazz.

Rutherford was one of the coterie of progressive musicians who played in the 1960s at the Little Theatre Club, off St Martin’s Lane, and he went on to found the Musicians’ Cooperative with Barry Guy, Derek Bailey, Howard Riley, Evan Parker, Tony Oxley and Paul Lytton, which played every Sunday night at Ronnie Scott’s Old Place on Gerrard Street. Simultaneously, both to make a living and to gain playing experience, Rutherford was a regular member of Mike Westbrook’s big band (and later his brass band), and worked with the fusion group Soft Machine as well as with the R&B group the Detroit Spinners.

In 1970 he formed his highly influential trio Iskra 1903 (its name inspired by the name of Lenin’s revolutionary newspaper which translates as “spark”, and “1903” to symbolise 20th-century music played by a trio). The fellow members were the bassist Barry Guy and the guitarist Derek Bailey and the group explored a range of original soundscapes that involved improvising without drums, documented on the album Chapter One and on the soundtrack Buzz, made for a movie by Michael Grigsby.

Rutherford was to continue with Iskra 1903 in various permutations, and also with larger groups, culminating in his Iskrastra, a big band which appeared occasionally during the 1990s, notably at the Bath Festival, and which broadcast on BBC Radio 3. For this band, Rutherford used a technique that he christened “comprovisation”, in which he composed the repertoire fully, but offered the players the freedom to substitute newly improvised ideas for the written parts.

This could often sound like unstructured mayhem, but at its best it could achieve moments of great beauty and spontaneity, the latter being one of Rutherford’s main concerns.

He played over the years with the Globe Unity Orchestra, the London Jazz Composers’ Orchestra, the Dedication Orchestra (commemorating the South African pianist Chris McGregor) and with Charlie Watts’s sprawling big band, which the Rolling Stones drummer ran in the 1980s as an alternative to his main job. Rutherford also played in many duo and trio settings, notably with the the German bassist Peter Kowald, and the saxophonist Evan Parker. More recently, Rutherford specialised in solo trombone concerts, which were entirely improvised, and some of which have been issued on the Emanem label.

Rutherford recovered from serious illness in 2001, and, although still prone to bouts of depression, went on to record with the rock duo Spring Heel Jack, and play at the Empty Bottle Festival in Chicago, where in 2002 he led an international sextet. Although at the time of his death interest in his work was growing in America, and he played at last year’s Vision Festival in New York, he was latterly seldom able to work in the UK and subsisted on his old age pension and a handful of paid engagements a year.

Paul Rutherford, jazz trombonist and bandleader, was born on February 29, 1940. He died on August 6, 2007, aged 67