One of the suspects in the murder of Drummer Lee Rigby is believed to have had contact with a “terrorist instructor” now in prison for running military-style training camps which were used by Islamist extremists including the 21/7 London bombers, The Independent has learnt.

Michael Adebolajo is understood to have attended talks given by preacher Mohammed Hamid, who called himself Osama bin London, and a bookstall run by Hamid in Marble Arch, central London.

There is nothing to suggest that Adebolajo was engaged in activities at the time which warranted deploying resources to track him during a period of intense militant Muslim activity.

Download the new Independent Premium app Sharing the full story, not just the headlines

Hamid, a 55-year-old former crack addict, was convicted of “grooming” young Muslim men for jihad. At his trial in Woolwich Crown court in 2008, the jury was played secretly taped recordings of him talking about the victims of the 7/7 bombings, saying: “Fifty-two? That's not even a breakfast for me,” and telling a comrade to be like “Jack the Ripper” and not get caught. Video footage was shown of a water melon being sliced in half amid cheering, in what was supposedly a demonstration of “beheading”.

Hamid, whose family came to Britain from Tanzania, was found guilty at the trial of three counts of soliciting murder and three counts of providing terrorism training, and jailed indefinitely, for a minimum of seven-and-a-half years. One of his followers, Atilla Ahmet, of Turkish Cypriot extraction, who had at one stage been a bodyguard for the radical cleric Abu Hamza, pleaded guilty to three counts of soliciting murder.

Among those who passed through the camps he organised, in Cumbria and the New Forest, were five men who were later convicted of the failed bomb plot of 21 July 2005. Hamid was accused of acting as the mentor of the would-be suicide bombers who wanted to emulate the devastation caused by the 7/7 attacks.

Hamid and 14 others were arrested and convicted in an operation, Overamp, in which crucial evidence was gained by an undercover police officer who had infiltrated the group, known only by his codename “Dawood”, as well as by bugs placed by MI5 in the homes of the suspects.

Members of the group were seized while they were sitting down for dinner at a Chinese restaurant. Detectives had found out about the meeting and location through surveillance; minutes before armed officers burst in, one of the suspects was heard to say “MI5 has probably bugged the place”.