HE was the most unlikely-looking hero. Balding, bearded and softly-spoken, he was more a favourite uncle than a man who changed the face of music in the UK.

But John Peel, who has died from a heart attack at the age of 65, influenced the musical tastes of more than one generation, not only by launching the careers of dozens of performers, but by his persistent championing of new sounds.

From glam rock to punk to drum 'n' bass to techno, he was there at the outset, introducing his army of devoted listeners to his latest discoveries, infecting them with his unbounded enthusiasm. Few DJs can lay claim to leaving such a mark on their audience.

The extent of his importance is reflected in his longevity at the nation's premier youth music station. He chalked up nearly 40 years at Radio One, where he was the only original DJ still broadcasting, and when he turned 65 in August he became the only pensioner fronting a show at the station.

His late-night show still ran three times a week, and in 1998 he became the presenter of Radio Four's Home Truths, which garnered four Sony Radio awards a year later.

But Peel, as befitting a self-deprecating broadcaster, was modest about his success, saying: "You can either see it as selfless dedication to public service broadcasting, or a shocking lack of ambition - it's both of those things.

"What I do is ideally suited to Radio One, and nobody has ever tried to lure me away anyway."

He was born John Robert Parker Ravenscroft in Heswell, near Liverpool, shortly before war broke out in 1939. His father owned a cotton mill, but Peel was later to say that his parents had both been distant, and he was brought up mainly by a nanny.

HE went to Shrewsbury School, and although he hated it, it was there that he experienced his musical awakening, when he heard Elvis Presley singing Heartbreak Hotel.

"Everything changed when I heard Elvis. Where there had been nothing there was suddenly something," he was later to recall.

After National Service as a radio operator in the Royal Artillery, he went to America in 1960. At first working as an office boy, as Beatlemania swept the country he became a DJ for WRR radio in Dallas, unashamedly cashing in on the new craze for everything British.

He returned to England in 1967 to work for pirate station Radio London, where his Perfumed Garden show became essential listening, with a playlist including The Doors, Pink Floyd and Jimi Hendrix. He also got the first play of The Beatles' Sergeant Pepper's Lonely Hearts Club Band. He then became part of the launch team for the new national channel Radio One, where he was to remain for the rest of his life.

From the outset, he was determined not to play by the rules. He would play tracks without interruption, filling the gaps between records with his dry humour and pertinent observations on the music, a world away from the transatlantic platitudes of many of his colleagues.

But it was as a patron of new music that really defined his contribution. In the early days, he promoted new acts including David Bowie, Marc Bolan and Captain Beefheart. Later he was among the first to spot the rise of punk, giving airplay to the likes of the Sex Pistols and the Clash, and then Joy Division and the Undertones, whose Teenage Kicks was to remain his all-time favourite single. He once said he would like the song's line, "our teenage dreams so hard to beat" on his tombstone. In the 1980s, it was The Fall and The Smiths who owed a debt to Peel for bringing them to a wider audience.

His Peel Sessions became legendary and hopeful bands from all over the world sent their tapes to him in the knowledge that he cared about the music.

The list of bands he helped introduce to the public includes some of the most influential acts of the last four decades: U2, Nirvana, Pulp, Roxy Music, The White Stripes, Rod Stewart, The Velvet Underground.

And his passion for new sounds remained undimmed. Even when he was twice the age of many of his Radio One colleagues, it was Peel who was at the cutting edge, his eclectic taste ensuring many new sounds were aired well before they made it to the mainstream.

He broadened his appeal with his first Radio Four programme, Offspring, from 1995-7, picking up a Sony Gold Award, before moving on to Home Truths in 1998.

HE received an OBE in 1998, was given a place in the Radio Academy Hall of Fame and in 1994 was given the NME Godlike Genius award. Earlier this year, he was voted the nation's fifth favourite Scouser, in a poll topped by Wayne Rooney.

A father of four, he lived in Suffolk with his wife Sheila, who was with him in Peru when he died, and was a fan of both the Archers and Liverpool FC. He listed his hobbies in Who's Who as making plans to live in France and staring out of the window. Three years ago, he was diagnosed with type II diabetes, and spoke frankly of the difficulties of adapting to living with the disease.

But for a man who made it his life's mission to seek out and promote new music, it was perhaps fitting that he died while on a working holiday to South America. Always looking for new sounds, he never gave up on the music.