He was the man who invented rap, "the black Bob Dylan".As lanky as a basketball player, he delivered jeremiads against racism and poverty, but with such nonchalant poise that he might have been a Harlem Globetrotter.
The phrase 'the revolution will not be televised' has entered the language
Jazzy grooves and deft lyrics took his records into the pop charts in Britain and the United States.
Alongside fellow music luminaries Stevie Wonder and Bob Marley, he successfully campaigned for the civil rights campaigner Martin Luther King to be recognised with a public holiday in the US.
But then something happened to Gil Scott-Heron. The records dried up. He stopped touring. He was arrested and jailed over possession of cocaine and rumours circulated about his health.
When I mentioned Gil Scott-Heron to friends and colleagues, the ones who remembered him at all had the same question: "Is he still alive?"
Spoken word experiments
In a supper club in New York City a few nights ago, a spare figure, rising on great spindly legs like a wading bird, loped on stage barely three-quarters of an hour after his allotted slot.
"Those of you who thought I wouldn't make it, you lose," he grinned. "Those of you who thought I wouldn't be here on time, you break even!"
I'm not Pablo Escobar. It was a mistake I made. I move on.
On being jailed for cocaine possession
With a tumbler of orange juice, Scott Heron toasted his long-suffering fans (and perhaps the intrepid Big Apple producer, Jill Newman, who had secured the booking).
Scott-Heron was born in 1949, the son of a Jamaican footballer who was the first black man to turn out for Glasgow's Celtic FC.
He was raised by his mother and grandmother in Jackson, Tennessee. At college, he encountered the verse of the black poet Langston Hughes, a discovery that led him to experimenting with spoken-word tracks on his early LPs.
The first of these was Small Talk at 125th and Lennox, a kind of oral blog from the projects, which included a stirring call to action entitled The Revolution Will Not Be Televised, a phrase which has since entered the language.
Voice of Tango ads
He was making pop music about the inequities of apartheid, with the track Johannesburg, a decade before Britain's Special AKA released Free Nelson Mandela.
Gil Scott-Heron's father was the first black player at Celtic FC
Other songs presciently addressed contemporary bogeys such as nuclear power (We Almost Lost Detroit) and the empty, sucking glamour of celebrity (Show Bizness).
Such uncompromising messages were not always welcome: "We weren't allowed to play everywhere. We had our records taken off the shelves," says Scott-Heron.
But there were unexpected perks, too. It was the poet's fathom-deep drawl that climaxed a memorable advertising campaign for a soft drink the colour of spray-tan: "You know when you've been Tango-ed!"
Elsewhere in Scott-Heron's repertoire, tracks dealing with substance abuse now have the terrible plangency of telephone calls to the emergency services which are replayed on television reconstructions.
"Down some dead-end street there ain't no turning back," croons the young Scott-Heron on Angel Dust. Or consider The Bottle: "If you see some brother on the corner, looking like a goner, it's gonna be me."
In Harlem last week, Newsnight was happy to treat Scott-Heron to a nourishing cheese-steak sandwich in a fortified deli.
It was just such a stockaded corner store, a liquor outlet called the Log Cabin, that inspired The Bottle, he said:
Gil Scott-Heron was doing rhyming and spoken word over a back-beat as long ago as 1970. The music that became hip hop and rap - that's what he was doing"
Richard Russell, XL Recordings
"I watched these people lining up every morning, bringing back their empties for a discount. I discovered one of them was an ex-physician, who'd been busted for abortions on young girls.
"There was an air traffic controller in the military - one day he sent two jets crashing into a mountain. He left work that day and never went back."
From the outside at least, the veteran soulman has endured a long night of the soul of his own.
He explained matter-of-factly that he was caught with some cocaine and did a year-and-a-half for it: "I'm not Pablo Escobar. It was a mistake I made. I move on."
Is he in a happier place now?
"Happier than in jail, yeah! I was unhappy in there, doing something I didn't want to do," he said. "But it's like a man with a broken leg - it heals, you don't talk about it forever."
"So you did some coke, now you don't?" I asked. "I didn't say that," came the answer.
It was while he was doing time that Scott-Heron received a visitor from London, a record producer called Richard Russell.
Watch a clip of vintage Gil Scott-Heron as he performs Johannesburg on the Old Grey Whistle Test in 1976
"Gil Scott-Heron was doing rhyming and spoken word over a back-beat as long ago as 1970," Russell explains. "The music that became hip hop and rap - that's what he was doing. He is undisputedly one of the people who invented that type of music. And it's gone on to be incredibly important, and affect the culture in an enormous way."
Rumours of a "new" Gil Scott-Heron album, like the reunion of the Friends cast, have circulated for as long as anyone can remember.
But Russell has guided the poet into the studio at last, and a long-player waggishly entitled I'm New Here will be released in February - Scott-Heron's first for 15 years.
He denies that his recent experiences have percolated into the record, though it is distinctly dark in places, dealing with his own upbringing "in a broken home" and including a cover of the Robert Johnson blues Me and the Devil.
The musician is taking on a limited number of concert engagements, and checking the proofs of a book about Martin Luther King, to be published by go-ahead British imprint Canongate.
As to what is on his own bedside table these days, Scott-Heron admits to a weakness for thrillers, the turf-and-treachery novels of Dick Francis especially.
As insights into the reading habits of black radicals go, it could scarcely be more nonplussing if Malcolm X himself was found to have been devoted to the Drones Club antics of Bertie Wooster.
Watch Stephen Smith's full interview with Gil Scott-Heron on Monday 16 November 2009 at 10.30pm on BBC Two, and afterwards on the BBC iPlayer and on Tuesday on the Newsnight website.
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