The exorcist Abou Mohammed sits cross-legged on the floor of a back-room in his home in Ilford, East London. He is surrounded by copies of the Koran, containers of olive oil and a spray-bottle of water which he uses on the Jinn, the supernatural spirits, that he says possess many of his clients.

Mr Mohammed, who goes by the title of Raqi, has a waiting list several months long and charges £60 for a one-hour session.

One of his clients is Mudasar Khan, 41, who says he has been possessed by a Jinn for years. He describes it as something that surrounds his body, buzzing, making him unwell and even stopping him sleeping.

Mr Khan has been on anti-depressants in the past and suffered panic attacks, but he says the Jinn prevented medication from working and that it is only coming to Abou Mohammed that has provided some relief.

"I had to go to the doctors and the hospitals too, to prove it to my family, because if I didn't do that side of it as well they'd think it was in my head," he says.

For five years Mr Khan has been treated by Mr Mohammed, who he says summons up the Jinn inside of him and speaks to it directly, easing its effect.

'Power to cure'

Mr Mohammed knows what he does is controversial - while we are filming his work he also films us, concerned that we will distort what he does - and he says that there are many charlatans in his field.

The exorcist believes some illnesses are unnecessarily dealt with by doctors when they are actually spiritual problems. He even says some people have operations they do not need because the Jinn has tricked doctors.