Twenty-six year old Lucas Kinney, the son of a British film director, has been revealed to be the figurehead for al-Qaeda in Syria, according to the Daily Mail.
Kinney is the first white British convert to emerge in Syria; he grew up in the home counties, went to Catholic school and, as a teenager, even spoke of being a priest.
He appears in a series of propaganda videos seeking to recruit IS jihadists to his al-Qaeda supported group known as Jabhat al-Nusra. He uses the name Abu Basir al-Britani.
His English accent remained apparent in the videos, where he is seen heavily armed, calling fellow Muslims to join him fighting Bashar al-Assad and Islamic State.
His father, Patrick, 59, worked with Steven Spielberg and was assistant director to a number of blockbusters, including Empire of the Sun and Braveheart.
His mother, Deborah Phipps, 53, shared her fears for her son with the Daily Mail.
"Lucas is a target. I'm glad he's associated with al-Qaeda rather than IS, but obviously I worry," she said.
"I last heard from him recently. I don't get anything for months and months and then all of a sudden I get an email and every time I think, 'Well, at least he's still alive'. That's the relief.
"He's married out there. I don't know anything about her. They don't have any children as far as I know, but this is recent, the last few months.
"We just want him to come home. If he's done something wrong I'd like him to accept the consequences. He's still young - and at least he's still alive."
Kinney grew up in the home counties, where he attended a Roman Catholic school, until his step-father got a job in Saudi Arabia and the family emigrated, before moving to Egypt.
In Cairo he gained GCSEs and three A-Levels from a top independent school.
He lived briefly with his father in Vienna before becoming a student at Leeds University, studying Middle Eastern Studies with Arabic.
After his first year, he dropped out and returned to Vienna with his father, where it is thought he converted to Islam.
Phipps told the Daily Mail that she only learnt her son was in Syria after her ex-husband called her to say he feared their son was dead after a picture appeared of him lying severely injured in a bed.
"He'd been struck by a mortar so his arm basically was hanging off," she said. "He had to have a big operation and he said he wouldn't be able to fight for about 18 months."
She said that her son's move to Vienna was when everything began to change:
"Lucas did not say he was becoming a Muslim, but we used to talk on Skype so we could see him, and you could see he had become a Muslim.
"He had a beard and the robes, it was quite obvious. After a while he moved out to live with friends. We didn't even really discuss it.
"When I found out he was in Syria I said, 'If I could get on a plane and come out there and bring you back, I would'. But he said, 'No, that's not what I want'. They have to want to come back, then maybe you can take steps."