For Keith Butler, it was a single anguished cry he wished he'd never made.

For the world of rock music, it was a defining moment that has become the stuff of legend.

Almost 33 years ago in Manchester, England, Butler's anonymous shout of "Judas" opened a major chapter in rock 'n' roll history. Now, an asthma attack and a trip to the local coffee shop has closed it.

In the process, the world is getting to know Butler, a shy ex-Briton who, truth be told, would rather remain unknown. But he thought he should set the record straight about May 17, 1966. That's the night Butler stood up in Manchester's Free Trade Hall and lambasted Bob Dylan with a single word heard round the world: "Judas!"

"The 'Judas!' shout, that's something that I hadn't talked about barely at all," he said. "It was embarrassing. It wasn't something you felt particularly proud of. That had been buried away."

That infamous shout and Dylan's contemptuous response — "You're a liar!" — are cited by many authorities as the watershed moment in Dylan's career.

The exchange could be heard on bootleg recordings for years before the show was released officially last year on Bob Dylan: Live 1966. Dylan's reply served as a declaration that the onetime folk singer's controversial foray into electric rock music was the right thing to do, and that history would bear him out.

Butler had been one of the non-believers.

"We were just really disappointed," he said recently. "That wasn't the Bob Dylan we'd been used to listening to. The Dylan we were used to was [the folk singer of 1963's] The Freewheelin' Bob Dylan."

Beginning with Bringing It All Back Home (1965), Dylan released a trio of albums grounded heavily in electric instruments. When he first brought the sound to American audiences at the Newport Folk Festival in 1965, he was booed. When he took the tour worldwide, his audiences went from being unhappy to labeling him a traitor to the folk movement.

But the man who crystallized those feelings by shouting "Judas" remained anonymous until last year, long after the moment had been written into history. He still might have been unknown had he not been struck with a bout with asthma the day before Live 1966 was released in October.

On that night, Butler, now 52 and living in Toronto, woke from an asthma attack and decided to take a walk to get some fresh air. He ended up in a coffee shop, where he picked up the Toronto Sun from the counter and spotted an article that inspired him to find out more about that night in 1966.

The story, by Associated Press writer Scott Bauer, described the impending release of Live 1966, as well as C.P. Lee's book about the concert, "Like the Night," and a rarely seen documentary on Dylan's '66 tour called "Eat the Document."

"So I'm on my own, in the middle of the night, in a coffee shop," Butler recalled. "And at the bottom of the article, it said, 'On "Eat the Document" can be seen some footage of people leaving the theater.

'One of them says, "Any bloody pop group can do this rubbish." ' And I recognized the words — it was staggering. It was an incredible shock ... from 30 years ago and 3,000 miles away, I was reading what I recognized as my own words."

In his book, Lee describes the entire concert as a "psychodrama," and anyone who has heard the verbal skirmish between Butler and Dylan will recognize it as the climax of that drama.

Dylan began the show with an acoustic set, playing songs such as "It's All Over Now, Baby Blue" (RealAudio excerpt). When he brought out the raucous, electric Hawks (soon to change their name to the Band) for the second set, the crowd turned on him. At several points, many of the 2,000 concert-goers clapped slowly and defiantly to show their displeasure and shake Dylan from his game.

Finally, during a period of silence after "Ballad of a Thin Man," Butler shouted his invective.

"Judas!" he cried.

"I don't believe you," the singer spat back. "You're a liar!" (RealAudio excerpt of exchange). Then the band crashed into the set closing "Like A Rolling Stone" (RealAudio excerpt), with Dylan commanding them to "Play f---ing loud!"

Dylan's venom sent the mortified Butler scampering out of the hall before "Like a Rolling Stone" got under way.

"Can you imagine what it's like as a 20-year-old kid?" Butler asked. "You were just crushed. I was totally embarrassed when he shouted back. I was there with another guy, and that's when we decided to leave."

While Butler tried to forget about the incident, the exchange sent shockwaves through the world of music and came to symbolize the point at which rock entered a new era, opening the doors to a more artful form of musical expression.

"It elicit[ed] from Dylan not just an angry response but a response that, in its own way, is pure music," said Greil Marcus, author of "Invisible Republic: Bob Dylan's Basement Tapes." (Marcus' "Days Between Stations" column appears monthly in Addicted To Noise.) "The way he says, 'I don't believe you,' is the essence of shock and disgust and disbelief, but all contained within a kind of cool, which he then immediately loses."

While Lee said the performance stood, on its own, as a great event, the shout catapults that night into something more meaningful, going so far as to call the event "Brechtian," referring to experimental German playwright Bertolt Brecht.

"Without the shout, that album [Live 1966] would be that much less important," said Lee, who has been haunted by the performance ever since he witnessed it live as a 16-year-old kid.

"Nobody could have scripted it better," he added. "If he shouted, 'Judas!' three numbers before, it wouldn't have had the same impact. Just before the last number, it's astonishing."

While the rest of the music world studied the event and analyzed its significance through the years, Butler said that he tried to forget the exchange. He now has two kids and a corporate job.

But in 1966, he was just a young man with a lot of ideals and little money. While he'd saved enough for a guitar — so among other things, he could learn Dylan songs — he never had the cash for Dylan records or a turntable to play them on.

To be called out in public by a singer that powerful was humiliating, he explained.

"My key memory was of the news crew," Butler said, referring to the filming of "Eat the Document." "Because that's the kind of story you tell over a beer. It's something different."

But after reading about the album, Butler traveled to New York to see "Eat the Document"; then he read Lee's "Like the Night." It was the book that inspired him to step forward to tell his side of the story, in particular Lee's notion that the shout — essentially branding the Jewish Dylan as Christ killer —

"To shout 'Judas' at a Jew in 1966 was an act of mind-boggling stupidity and senselessness," Lee writes.

Late last year, Butler flew to England at his own expense for a BBC Radio One documentary about the concert. Interviews with him and his companion at the concert, Chris Cuttance, along with comparisons of Butler in person with footage of him in "Eat the Document" and accounts from other concert-goers at the show all convinced both the BBC and Lee that Butler was the infamous shouter.

It was on the steps of the Free Trade Hall that Butler and Lee finally met, just before filming of the BBC documentary began. Later the two went out for a drink. "He said, 'I just want people to know that I wasn't an anti-Semite,' " Lee recalled.

Mickey Jones, who played drums with the Hawks on that tour, said that after listening to the BBC program, he's convinced Butler is the infamous shouter, although he didn't hear the exchange during the concert. He remembered laughing as he listened to tapes of the performance afterward.

"It was just a gig," said Jones, 57, who in the '90s has focused on acting, with a recurring role on TV's "Home Improvement." "I don't think anybody feels like they are creating history when they do something. We certainly didn't. It was a gig, we were having fun. We knew that we were giving them good music, even though we got booed everywhere we went."