Video report by ITV News Security Editor Rohit Kachroo
The parents of Jihadi Jack missed the opportunity to stop their son travelling to Syria to fight for Isis, a friend has told ITV News.
Anwar informed John Letts and Sally Lane that he thought Jack was planning to travel to Syria but they did not believe him.
The suspicions of Anwar were aroused when Jack insisted on returning items owned by his friend before travelling abroad, which he claimed was for a short trip to Kuwait to learn Arabic.
"I jumped on my bike and I cycled as fast as I can, I was thinking 'this guy is doing some stupid stuff now'.
"I went to his parents' house and I thought his mum would open the door but it was his dad and I said: 'Listen, I am worried about Jack, you need to take his passport or I am going to report him to the airport because I think he might be doing something like go to Syria'."
Despite the claims of Anwar, Mr Letts and Ms Lane believed that Jack was merely planning to travel to Kuwait in order to study Arabic.
"His dad was obviously surprised, he wanted to know more, naturally. We sat down, I was hoping his mum would be a bit more 'thingy'.
"I felt his parents were being a bit naive 100 per cent because when I spoke to his dad, he was shocked; he was concerned but there was no action. And I was thinking 'man, if I know that's my son, you're getting two slaps and you're going nowhere'."
Anwar sat down with Jack's parents to discuss the severe prospect of the teenager travelling to Syria where he would eventually join Isis.
Jack denied that he planned to travel to the country, with his parents accepting his explanation about Kuwait.
"I sat and chatted with his dad for hours [about going to Syria] and he said 'I don't think so, he wants to study Arabic, he's been talking about it for a long time'. So he's been telling his parents what they want to hear.
"His dad didn't believe, he didn't take it as seriously as I thought they should have."
Jack did travel to Syria, resulting in his mother frantically calling Anwar to get his advice on the matter.
"Some time went on and then I got a phonecall from his mum crying on the phone.
"She said 'Jack's gone' something like, 'I need you to come' ... I came. 'Jack's just called us from Syria' ... my heart was like ... 'what has this guy done? Are you serious?' I was shocked, his mum was crying, it was really, really bad.
"What he put his mum through, you wouldn't want to do to your worst enemies.
"She lost, literally, half her weight in a matter of days, that's how much of a shock it was."
Oxfordshire-born Jack contacted Anwar from Syria but his friend could see that his former friend had been changed by the move.
"When he contacted me it was like I was speaking to a different person. He started to hold extremist ideas. He said to me 'you used to be the most dearest brother to me and now I see you as an enemy."