Al-Qa'ida's attacks on London in the summer of 2005 exposed Britain's vulnerability to a new kind of terrorism.
The discovery that the July bombers and their accomplices were home-grown meant the police and the Security Service needed to rethink their counter-terrorism tactics. The subsequent hunt for groups of British-born men who might be planning similar attacks was given the highest priority.
Key to the new approach would be deeper penetration of Muslim communities. The police worked to gain the confidence of Muslim leaders; the Security Service stepped up its recruitment of informers.
Some of the intelligence obtained was key to foiling major terrorist attacks but there were also mistakes. The raid on the home of two brothers in Forest Gate, London, resulted in one of them being shot and both being exonerated. This year, the arrests of 11 Pakistani students and one British student ended in embarrassment when the raids were brought forward and the men were all released without charge.
Undaunted by the errors and damaging impact these tactics were having on Muslim communities, MI5 has pressed on with its recruitment drive.
While a few of these "spies" will be crucial to counter-terrorism operations, many will be of little or no intelligence value while others targeted will be hostile to the crude approaches of MI5 officers. The six north London men who say they have been targeted allege they have been blackmailed and intimidated by the Security Service.
For months, the men kept their contact with MI5 secret and did not even confide in their families. "No one wants to be accused of spying on their own community, people would never trust you," said Mohamed Nur, one of the men that MI5 approached. "I would not be able to work or live here again."
Only when Abshir Mohamed decided to tell the chairman of a north London community centre about his MI5 encounters did the scale of the intimidation and harassment emerge.
Shaharbeen Lone, a Kentish Town Community Organisation leader, said: "Abshir called me when he reached home [from Heathrow, where he was quizzed], extremely worried and very anxious. His mother and wife, who has just had heart surgery, had been travelling with him and had to wait throughout his ordeal. Abshir is a senior youth leader who works hard to stop young Muslims getting involved in crime."
Mr Lone called a youth leader meeting to see if others had similar experiences. What he heard appalled him. Two men said they had been detained abroad and interviewed by MI5 upon their return to the UK. Another was questioned when he returned from his honeymoon to Saudi Arabia. Two more were visited by MI5 agents at home.
MI5 wanted to use the men as informers. Those who refused to co-operate received threatening phone calls.
Born in Somalia, the men had all come to Britain as children. Growing up in north London, they had overcome troubled backgrounds, which had occasionally brought some of them to the attention of the police. To escape these influences, their families sent them to study Arabic in Cairo. But none of them, says Mr Lone, who has known them for years, has held extremist views or had links to terrorism. Today they lead exemplary lives. The organisation's chairman complained to the local MP, Frank Dobson and to police. The police told him they would tell MI5 of his concerns.
Mr Lone says by the end of last year the message seemed to have got through and the intimidation ended. Then last month, MI5 agents questioned Mahdi Hashi at Gatwick and told him if he didn't spy on his friends, he could expect to be locked up at airports for hours. "It has started again. There seems to be nothing we can do to stop them ruining these young men's lives," says Mr Lone.Reuse content