Newsnight has discovered that some of those who were alleged to have helped the men involved in the London bombings and the Crawley plot are still walking the streets of Britain.
During the course of our investigations we confronted two of them on camera. One was a man known as "Q" from Luton. The other was Sajil Shahid whose last known address was in Barking.
Evidence which helped convict the Crawley bombers came from Junaid Babar - a self-confessed terrorist who did a deal after he fell into the hands of the US.
According to his witness statement "Q" sent Mohammed Sidique Khan (MSK) - the leader of the 7/7 bombers - and Omar Khyam - the leader of the Crawley plotters - to Pakistan.
There they trained at a terror camp set up by Sajil Shahid. They fired various weapons including pistols, rifles and rocket-propelled grenades and Omar Khyam was shown how to make bombs.
Newsnight has learned that MI5 had "Q" - full name Mohammed Qayum Khan - under surveillance as early as March 2003.
They suspected him of helping extremists linked to al-Qaeda in the tribal areas of Pakistan.
They taped him talking to Mohammed Sidique Khan two years before the London bombings. They also put Mohammed Sidique Khan on their database although they say the conversations were not about terror.
We wanted to ask "Q" if it was true that he had sent Mohammed Sidique Khan to Pakistan for terror training
Again according to Junaid Babar, he and Sajil Shahid travelled to the district of Malakand on the al-Qaeda controlled Afghan frontier areas in 2003 where they set up a terror training camp.
"Q" in Luton allegedly sent Omar Khyam and Mohammed Sidique Khan to Lahore in July 2003. Babar then met them both at the airport along with some of the other Crawley plotters.
They all went to the Malakand training camp.
We wanted to ask "Q" if it was true that he had sent Mohammed Sidique Khan - the man responsible for the murder of 52 people in London on 7/7 - to Pakistan for terror training.
We tracked him down to a sandwich bar in Luton but he would not answer our questions and we were thrown out.
We also wanted to speak to Sajil Shahid - who helped set up that camp and whose name was referred to during the trial. Sajil was the leader of Al Muhajiroun in Pakistan.
Al Muhajiroun was the movement originally set up by the radical preachers Abu Hamza and Sheikh Bakri Mohammed at the Finsbury Park mosque in London.
Almost all of the terror plots are linked to those preachers and the key characters all went for terror training in Pakistan.
Sajil Shahid is alleged to have set up terrorist training camps
For example, the so-called 20th hijacker from the 9/11 plot Zacarias Moussaoui worshipped with Abu Hamza at Finsbury Park as did the shoe bomber Richard Reid.
The 7 July London bombers Mohammed Sidique Khan and Shehzad Tanweer were Al Muhajiroun members. The Crawley plot leader Omar Khyam was recruited by Sheikh Bakri.
The British suicide bombers Asif Hanif and Omar Sharif - who blew up Mike's Bar in Tel Aviv in 2003 murdering three people - were also Al Muhajiroun recruits.
Many of them went through the Al Muhajiroun support network in Pakistan.
In the past Sajil Shahid has proudly boasted to the Pakistani media of his leadership of Al Muhajiroun.
Since 7 July he seems to have become rather shy and refused our requests for an interview about the terror training camps.
We discovered last year that he had returned to the UK and we traced him to an Islam Exhibition at the Alexandra Palace in London.
He again refused to answer questions and denied what he had so often told the Pakistani press.
Up to 3,000
The evidence is that "Q" sent radicals to Pakistan.
There they went to training camps organised by Sajil Shahid amongst others and returned to Britain to commit mass murder and plot bombings.
MI5 believe that as many as 3,000 have returned to the UK after terror training at these and other camps in the region.
Newsnight's full investigation can be seen on BBC Two and live on the Newsnight website on Monday April 30 at 2130BST/230GMT