LONDON — Several opportunities to stop the bombers who tried to attack London’s transport network on July 21, 2005 were missed, it can be disclosed following the conviction yesterday of one of the most senior terrorist recruiters in Britain — a man who called himself “Osama bin London.”

Mohammed Hamid, a street preacher who once told young Muslims that the 52 deaths in the July 7 attacks on London that year were “not even breakfast to me” — groomed the would-be suicide bombers under the noses of watching police, security services, and even the makers of a BBC documentary.

Mr. Hamid, 50, who is believed to have met senior Al Qaeda figures in Afghanistan, organized training camps in the New Forest, the Lake District and Scotland, and paintballing sessions in Berkshire and Kent.

He also held prayer meetings at his home in Clapton, east London, where he would urge Muslims to attack nonbelievers.

All four of the failed suicide bombers of July 21 attended his meetings and Mr. Hamid ran an Islamic bookstall on Oxford Street with Muktar Ibrahim, the leader of the gang.

He was spoken to by police at his Oxford Street stall on three occasions before July 2005 and on eight separate occasions afterwards but was not arrested until September 2006 after an undercover policeman infiltrated his group.

He was found guilty of organizing terrorist training camps and encouraging Muslims to murder nonbelievers at the end of a four-month trial at Woolwich Crown Court.

Police first observed the July 21 bombers in the Lake District at one of Mr. Hamid’s camps on May 2, 2004. Following a tip-off, a Cumbrian officer watched 20 men training in Great Langdale as Mr. Hamid barked orders.

Special Branch was called in and close-up surveillance pictures showed all four of the men who went on to try to attack London’s transport system the following year.

Mr. Hamid’s home in Hackney, east London, was subsequently put under surveillance and four weeks later, on May 29, he was seen gathering another group to return to Great Langdale.

Once again the Cumbrian officer located them in the Lake District and this time the surveillance was left to the local police who saw the group “holding branches or sticks as though they were carrying rifles.”

The case was handed over to MI5, who watched the group in August 2004 as they performed press-ups, sit-ups, an anti-ambush drill, and “leopard crawling” — moving low and flat along the ground.

Three other men — Kibley da Costa, 24, Mohammed Figari, 42, and Kader Ahmed, 20 — were found guilty of attending terrorist camps in the New Forest and at a Berkshire paintballing center.

Atilla Ahmet, 43, who was Abu Hamza’s right-hand man at Finsbury Park Mosque and the self-styled emir of the gang, admitted three charges of soliciting murder at the start of the trial.

During Mr. Hamid’s trial, the court heard how he and Mr. Ibrahim had a stall selling Islamic literature outside Debenhams in Oxford Street. They were arrested in October 2004 following reports of men blocking the pavement and as Mr. Hamid was handcuffed and dragged to the police van he told the officers, “I’ve got a bomb and I’m going to blow you all up.”

At the police station Mr. Hamid gave his name as Osama bin London and was identified only after a fingerprint check that showed up his criminal record.

Perhaps the ultimate irony came when Mr. Hamid was recruited from his stall to represent the acceptable face of Islam in a BBC documentary called “Don’t Panic I’m Islamic.”

He was filmed in February 2005, along with Mr. Figari and 14 other men, at a paintball center in Tonbridge, Kent. The documentary was broadcast in June 2005 and the producer returned to talk to Mr. Hamid as police hunted the July 21 gang. He admitted knowing them and was “agitated and worried” but the producer claimed that her bosses took the decision not to notify the police.

Mr. Hamid exchanged 155 calls and text messages with the four July 21 bombers. He also sent Mr. Mohammed and Mr. Osman a text on the night of July 21 and attempted to ring both of them the following day.

MI5 put a recording device in Mr. Hamid’s home in September 2005 and in April 2006 an undercover officer infiltrated the group. At a meeting at his house in June 2006, Mr. Hamid told his followers: “The whole aspect is for you to get shahada [martyred] for you to be shaheed [martyr],” he added. Mr. Hamid and Kibley da Costa, 24, of West Norwood, south-east London, were also found guilty of providing training for terrorism. Mr. Figari, 42, of Tottenham, north London, and Mr. Ahmed, 20, of Plaistow, east London, were found guilty of receiving terrorist training. Two further members of the gang, Mohammed Kyriacou, 19, and Yassin Mutegombwa, 23, admitted attending terrorist training camps.