John Peel had all the evangelical zeal of the adolescent music fan in his approach and attitude to music. As rare a person as the music he played, his dry, hesitant, Scouse-tinged voice is, for many, synonymous with the touching memory of a tingling musical discovery. . . the first time you heard Sheena Is A Punk Rocker; the first time you heard Ireland's answer to The Beatles (clue: they're from Derry and Peelie adored them); the first time you heard Johnny Marr's head-spinning guitar intro to This Charming Man.

And the last time you twiddled the knob over to that all too familiar wavelength, he was still at it - playing some discordant sound by some teenagers from Dunfermline, but that was fine because you knew you weren't too far off hearing a Fall song. And if not Mark E. Smith hectoring us about society's evils, maybe he'd play Laura Cantrell or Gang of Four or The Skatalites. Or none of the above, maybe just something strange, dark and beautiful instead. . .

It was despite, not because of, the fact that he was a DJ that John Peel had such a massive influence on contemporary music. It's difficult to give him the same job description as those jibbering fools who clutter up the airwaves now; hyperventilating as they introduce the new single from Girls Aloud. At BBC Radio 1, Peel was an untouchable simply because he knew more than the rest of the station combined, not least that the very best music can frequently be found off-road.

His very status as an outsider did mean that he was, as they say, cautiously scheduled, but it also meant that he developed an unalloyed trust with his listeners - he was rightfully scathing of corporate interference into musical affairs.

For musicians, he was the only DJ who really mattered. A thumbs-up from Peelie may not have sent you in with a bullet to the top 10, but it was a crucial seal of approval - a rite of passage for young tyros. And a John Peel session? It's still prized more highly than an NME front cover - and rightly so.

After his early days on a Dallas radio station (if you look really closely at the famous footage of Jack Ruby shooting Lee Harvey Oswald, you can just about make out Peel standing behind Ruby - strange but true), where he was a strict rhythm 'n' blues specialist, he returned to Britain to work with the pirates before going legit with Radio 1.

The station managers despised him - he played stoner music (The Doors, the Floyd - only broken up by judicious amounts of Hendrix) - and wanted him to be a bit more poptastic. Within his first week, he had been marked down as niche/special interest. So niche and special interest that he was the first DJ to play and champion Roxy Music.

It might surprise people how much he loved Roxy Music and Rod Stewart (he once appeared on Top Of The Pops with Rod Stewart's band), but Peel was eclectic before the term came to mean someone who plays a wide variety of bad songs.

He wisely sat out the more egregious excesses of prog rock, contenting himself with playing fantastic music off the Trojan record label and, when punk broke, he metaphorically cut his hair and took in his flares. While the Smashies and Niceies around him were unilaterally "banning this filth", Peel was galvanised and short, sharp, shocked his way through the late 1970s, early 1980s.

The Undertones scored a major label deal only because he played Teenage Kicks twice in a row - a song he couldn't listen to without bursting into tears. Bernard Sumner acknowledges that "if it wasn't for John Peel, there would have been no Joy Division". Members of The Smiths, Blur, Radiohead and the Manic Street Preachers (among hundreds of others) have all expressed similar encomiums over the last few days.

As in the film industry, nobody knows nothing in the music industry. Except for John Peel, who knew all that was worth knowing and played all that was worth playing. Teenage kicks all through his life.