None of the men realised they were already being monitored by MI5 and the police.
Investigations by Britain's domestic security service, MI5, can include undercover surveillance, phone tapping and communications intercepts.
In 2012, the head of MI5 Jonathan Evans said the scale of attacks was "astonishing".
Following their arrests, it emerged that Uddin was already known to the police and MI5.
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MI5 once listened in as he told a particularly incredible story of evading a US drone.
But it is obvious from notes on documents that MI5 had another file on Ronald Penrose.
There are four main types of threat that MI5 is on the lookout for.
Two years ago the MI5 spoke openly about their drive to broaden recruitment among ethnic minorities.
The 51-year-old said he had returned to highlight his ongoing pension dispute with his MI5 handlers.
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It tells the story of a republican woman in Belfast who is recruited by MI5.
It was selected by a judging panel including broadcaster Kirsty Wark and former MI5 director general Dame Stella Rimmington.
MI5, where American spies, not policemen, can get on with their trade, is fairly clear.
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Officials from the Security Service, MI5, leaked to the media in August that they had questioned her.
MI5 drew up a list of 55 suspects who had come into contact with Mr Khyam's group.
MI5 witnesses appear and give evidence - albeit as a disembodied voice from behind a thick curtain.
It has a combined staff of about 6, 000 agents, next to 3, 500 at Britain's MI5, for instance.
Britain's domestic intelligence service, MI5, says that three-quarters of the plots it faces have links to Pakistan.
MI5 agent, has escaped the clutches of the Official Secrets Act only by going into hiding abroad.
But it has emerged that an earlier draft of the judgment contained much more sweeping criticism of MI5.
But still, her MI5 file remained open - and when she returned to London, officers opened her mail.
MI5, Britain's domestic intelligence service, though his full comments are censored in the public version of the report.
Two people on the 1992 list, the heads of MI5 and MI6, were top secret in those days.
MI5 picked up some of Khan's conversations with Mr Khyam, and said these dealt mainly with financial scams.
Reading the report, I think it is unreasonable to blame MI5 for the actions of four deluded men.
Overall, I think MI5 have done very well given the amount of intelligence they have to go through.
She was being briefed by ex-MI5 officers who came into the palace to advise her on her security.
MI5 with bringing up two children, and the workload of the job eventually helped to break up her marriage.
They claim the UK government, including MI5 and MI6, failed to stop their detention or were complicit in it.
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In December Gordon Brown said that three-quarters of domestic terrorist plots being monitored by MI5 had links to Pakistan.
Mr Duncan Smith said all asylum seekers should be housed in secure centres until vetted by MI5 and MI6.
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