Did the 7/7 bombers come from Bakri's circle? "Probably not - it's something far more insidious," says Mr. Malik. "It's beyond the Omar Bakris; it's a low rumble."
Abu Osama, just 30, was born and raised here in East London, amid peeling paint and dingy kebab shops. "I know English. I know Britain. But if I live here, I must speak for Muslims elsewhere," he says, stressing that he belongs first to the ummah, or global Islamic community.
Abu Osama's faith deepened early. Watching his Pakistani immigrant father struggle to support his family of seven, he sought strength in Islam.
"I began praying and studying when I was 16, and since then I've been like this," he says, pointing to his long, curling beard.
Abu Osama first spoke publicly eight years ago; he has since won ardent followers.
Last fall, addressing a meeting of scores of British radicals, he sighed: "At the moment in Britain there is no jihad." Faces fell around the hall.
"Yet!" he exclaimed suddenly, to approving murmurs. The jihad would soon come, Abu Osama predicted, and he urged his listeners to embrace its arrival.
On 7/7, the jihad came. The suicide bombers were aged 18 to 30 - the same age as Abu Osama's cohorts. By portraying militancy as the ultimate expression of piety, Abu Osama and preachers like him are leading young Muslims down the path toward violence.
"Some of the people tell you Islam is a religion of peace because they think that then you'll want to convert," says Dublin-born convert Khalid Kelly, who soaks up Abu Osama's sidewalk sermon. "But you cannot possibly say Islam is a religion of peace; jihad is not an internal struggle."
Armed struggle was the last thing on Mr. Kelly's mind until his conversion several years ago. "I was your average Irish drunkard, partying and so on," he says. Arrested in Saudi Arabia, where he worked as a nurse, for brewing his own alcohol, Kelly found Islam in prison - an increasingly common arena for Muslim conversion and radicalization.