London (CNN) -- Since 9/11 around 250 Islamist extremists have been imprisoned in the UK after being convicted of terrorism-related charges.
But in the last few years, dozens have been released after completing their prison terms, some of whom have been angered and hardened by their time in prison, creating a major security headache for British authorities in the run up to the Olympic Games.
British newspapers have run full page stories on this threat with pictures of several high profile convicts being released back onto UK streets: "Games Fear Over Evil Fanatics," stated one headline last year.
But now, in an unprecedented interview, one of the released terrorists whose picture was featured in the newspaper reports is speaking out, describing to CNN not only how his life was turned around by an inspirational veteran cagefighter with a pioneering approach to deradicalization, but how under his guidance he has begun to confront al Qaeda's extremist ideology on the streets of London.
It is the first time a convicted Islamist terrorist in the UK has provided a television interview in the post 9/11 era, and one of the first interviews of its kind anywhere in the West.
Abu Bakr Mansha, now 28, a British Muslim of Pakistani descent, was convicted of terrorism in 2005 in a plot to kill or severely harm a British soldier, and served time in some of Britain's highest security prisons. But several weeks ago, we sat down with Mansha, a heavily bearded young man with a wiry athletic frame and a gap tooth grin, in a former British army gym in a military barracks town just outside London, which is now used by his new mentor Usman Raja to coach cage-fighting.
The two first met in Woodhill High Security prison in early 2011, Raja says, after Mansha wrote a letter asking for his help. By then Raja had developed a reputation among convicted Muslim terrorists -- and British authorities-- as a man dedicated to helping them find a new life and with a success rate that demanded respect.
"We clicked straight away. We got on very well because we have got a lot of things in common. Our family backgrounds are the same, we come from the same place back home," Mansha told CNN.
They had quickly established that both their fathers had known each other in Rawalpindi, Pakistan.
Mansha had heard of Raja's work via the imam at the jail, north of London.
He was also intrigued by Raja's record in cage fighting, or Mixed Martial Arts, a discipline Mansha had already started inside jail.
But at that time what Mansha most needed was someone with the ear of British authorities to help ease conditions for him in prison.
Raja vividly remembers his first meeting with Mansha.
"Just going into the prison it always shocks me. You never become desensitized to the high fences, the security doors. I had to wait the extra 10 minutes while they went away and got Abu Bakr from segregation," he told CNN.
Mansha had been sent to solitary confinement after fights with other inmates, which he claims were provoked by hostile prison wardens.
"Straight away there was a good connection," said Raja, who was also struck by Mansha's almost hyperactive energy. "I was dealing with an individual who came from the real streets of east London," he recalled.
Mansha was due for release about two months later. Raja promised himself he would do what he could to help him.
"The thought came in to my mind. "Let's plan, let's do something constructive and get a support structure there. How can we use that God given energy to do something positive?""
Raja knew he would have a challenge on his hands. He said Mansha had already been released once from jail in 2009 under strict conditions. But his attitude towards probation officers had been so bad that just a few months later he was assessed as still dangerous and recalled back to prison.
Mansha started training with Raja immediately after he was released the second time from prison in March 2011.
Like with other young convicted terrorists being released into his care, Raja used mixed martial arts to give him something else to focus on, and as a way to break him out of his radical mindset.
Mansha soon set himself a goal to become a coach like Raja. "I could channel my energy straight away and build something for myself," he told CNN.
Mansha's family background was by most definitions middle class. Raja says Mansha grew up in Tower Hamlets, an immigrant neighborhood in east London. His parents and extended family owned a row of houses along their street. His father ran a travel company organizing trips for pilgrims to Mecca in Saudi Arabia.
But Mansha, like a significant number of other British-Pakistanis growing up in east London, was drawn into a "gangster" street culture hostile to mainstream Britain, according to Raja. That hostility intensified when U.S. and UK troops invaded Iraq in 2003.
Mansha said: "I left college, left my studies, just went out with my friends on the streets, messing around, not going home. We loved getting in to fights ... that was east London."
Acquaintances told CNN, during this period he became increasingly religious, growing a thick beard.
In 2005, at the age of 21 Mansha was convicted of terrorism. Authorities called it a thwarted plot to kill or severely harm Corporal Mark Byles, a subsequently decorated British soldier who had returned home from fighting in Iraq.
When police raided Mansha's east London residence they found a blank firing gun being converted to live rounds, a balaclava, and a newspaper article with Mansha's fingerprints on it, featuring the soldier with a paragraph circled which read "Corporal Byles of Portsmouth, Hants, reckons he killed between 15 and 20 insurgents during the war."
They also found a piece of paper with Corporal Byles' former address and the word "hero" written on it in Mansha's writing, and DVDs featuring anti-Western propaganda, including footage of Osama bin Laden and a video of a British hostage being beheaded by al Qaeda.
Mansha still maintains he never plotted to attack the British soldier.
"The flat at that time, there was a lot of junk there ... no one ever cleaned up. Police picked up little pieces. I understand how they saw it, they put all this stuff together, therefore something was going on." Mansha told CNN.
All Raja knew for sure was that he was dealing with a young man who had become radicalized.
In prison Mansha had had time to reflect, making him more open to Raja's message on his release.
Once he had won Mansha's trust, Raja impressed on him that true Islam was spiritual, tolerant, and humanistic, and nothing like the narrow-minded divisive message he had been previously exposed to.
After his release, Raja and his small team spent countless hours counseling Mansha at a variety of locations in east London, including after prayers at mosques and after martial arts training sessions at gyms. During these sessions, Raja encouraged Mansha to ask deep searching questions about his faith.
Raja says that like most of his cases, there were moments of frustration, and he has sometimes had difficulty getting Mansha to focus. "My transformation came over time," Mansha told CNN.
Mansha says he has been strengthened by his new religious understanding. "I didn't know much about my faith. When I was younger I went to the mosque, I studied the Quran but it was in Arabic so I didn't know what it was saying," he told CNN.
"It's a big change, a big change, what I know now, my knowledge and my studies, what I know now, how I feel and how I think now."
Mansha's beliefs are reinforced in talks with Raja's spiritual teacher Sheikh Aleey Qadir, a Malaysian cleric in east London from a school of Islamic learning that traces its lineage of learning directly to the Prophet Mohammed.
"A real transformation comes over him when he sits down with the Sheikh - he becomes all quiet, very much the model pupil," Raja's wife, Khadija, said.
Raja also got Mansha to re-engage with the British value system. "Take away someone's hate and they feel liberated," Raja told CNN. "Once these guys are given back their sense of belonging to society they want to give back that energy."
Mansha's horizons were widened by his MMA training sessions. Most of the other fighters being trained by Raja were white working class; joshing around with them in the gym, and being accepted by them, helped change Mansha's worldview.
Mansha's loyalty to Raja's message was illustrated when one day Anjem Choudary, a prominent east London radical Islamist who helped build up al Muhajiroun one of the UK's most notorious pro al Qaeda groups, came over to shake Mansha's hand to congratulate him on his service to the cause, according to Raja. "I'm not with you. I'm with Usman Raja now," Mansha replied, according to what he later told Raja.
"If he has changed his views and he does stand with Usman Raja obviously that is his choice. At the end of the day this is a grave mistake because these people don't represent Islam," Choudary told CNN.
Choudary added: "People like Usman Raja have apostated from Islam ... they have gone outside of the fold of Islam because of their allegiance with the British government against their community."
The new Mansha is trying to stop other youngsters going down the path he did. "I learned the hard way," he told CNN.
"I see the youngsters now, their understanding is very limited, narrow minded," Mansha told CNN. "We have to get out there ... put ourselves out there. I'm doing that in my community. I'll do anything for them youngsters ... put them in the right line."
One example of his outreach work was persuading a British radical who had unceremoniously set fire to a large paper poppy, the British symbol of remembrance for their war dead, to see the error of his ways.
The stunt, which was captured on film, had been organized by Choudary's group, then operating under the name Muslims Against Crusades, on November 11, 2010 - Armistice day - while Mansha was still in prison, and had caused outrage.
"If someone burned the Quran, I know what I'd be thinking, what I'd feel, every Muslim would be feeling. I did speak to that brother when I came outside ... he realized his mistake," Mansha told CNN.
Now Raja believes Mansha, and other rehabilitated terrorists he has worked with, could be effective in carrying a message of tolerance to east London streets.
"Their whole future is going to be marked by being a convicted terrorist. So we tell them if they had never gone down that path they would never have met us and been given the chance to help others. The key is to give them a sense of purpose."
CNN's Ken Shiffman contributed to this report.