I'm sitting in a café in a grimy part of north London, whose exact location I can't tell you, drinking coffee with a man whose name I can't reveal. This man - I'll call him Ahmed - is apparently so dangerous that our government is not only eager to deport him to Algeria, but is keeping him under a kind of house arrest in the interim.
Ahmed's movements have been confined, for almost six months, to a small area around his flat, which takes him just 20 minutes to walk through. He is not allowed to use the internet or a mobile telephone, between 4pm and 10am he must stay in his flat and, while there, he isn't allowed to receive visitors unless they've been vetted by the Home Office. "I am a dog on a lead," he says. "I am not really a human being."
It would take a longer article than this to detail the twists and turns of Ahmed's situation, but five years ago he was given asylum here, and was a happy man. "That was like a dream coming true," he says. For two years he worked hard, going to college and opening an Islamic bookshop, but then he was arrested and charged with being part of the suspected terrorist conspiracy to make ricin. He was acquitted, and says of the jury: "My gratitude and thanks went to the British people." He got a job in an internet shop and started to build his life up again.
Then, in September 2005, the door of his flat was smashed down by police and he was arrested again, not on a criminal charge but because the government wanted to deport him for being a threat to national security. For five months, he was detained, but now, while his case is being considered by the Special Immigration Appeals Commission, he is living under these strict bail conditions.
Ahmed is not allowed to work and has no social life. "People now are so scared of me," he says. "I am just watching television, reading the papers, sleeping, going mad bit by bit. I am on antidepressants, I am epileptic now, I have asthma now." He has to report to the police station every day. "They say I can walk in the park. I feel like a pervert. Everyone in the park has company. Only I am not with anyone." Above all, fear of the future preys on his mind. "This is psychological torture. Whenever I have thought it was finished, it is still going on. I feel I will be a target now all the time. When I was in Algeria I had the opportunity to fly, but here I can go nowhere. I have tried to kill myself twice. Because now there is no future."
The government says Ahmed must be deported because there is evidence against him that could not be brought out in open trial. Without being able to see the evidence, Ahmed can only counter it with denial. He admits that he was once a sympathiser of the Algerian Islamist party the FIS, but says he was never a member and never espoused violence. He tells a convincing story of being an idealistic student, shocked by official corruption, who saw his teacher and hero killed by government forces.
He says he was not politically active after leaving Algeria and is not very religious, and he talks positively about living in an open society. Of course, this may be a front designed to disguise terrorist sympathies, but until the British government produces some evidence against him, it is very hard to judge.
Algeria's president, Abdelaziz Bouteflika, met Tony Blair at No 10 on Tuesday to set his stamp on a deportation agreement between his country and the UK so that Ahmed and others in his position can be sent back. Yet this spring Amnesty International published a report showing that Bouteflika has failed to stamp out torture and secret detention by military police.
"The government here agrees that if I am sent back I will be arrested," says Ahmed. "And then I know I will be tortured, if not straight away, then after a while. They might let me go, but then take me back to prison, or kill me." I ask Ahmed whether he can understand why the British people feel that men like him should be sent to face that situation. "I wish that the people who think I am dangerous would come and talk to me," he says. "I am not the scary one here."