Unseen footage of the British man thought to be the new Jihadi John - Siddhartha Dhar - has been shown on a Channel 4 documentary in which he speaks of the "real possibility" that the Islamic State flag will one day fly over Downing Street, and other extremists are seen laughing after watching execution videos.
In the documentary, titled Jihadis Next Door, Siddhartha Dhar, who changed his name to Abu Rumaysah after converting to Islam, shows filmmaker Jamie Roberts around a garage in east London that contains the IS flag.
Later he warns: “One man died in Woolwich, Lee Rigby, and the whole country went up in uproar, there are many Lee Rigbys in Muslim countries … and if these issues aren’t addressed we can expect more carnage in this country and more cycle of violence."
The footage was shot by the broadcaster in January 2014, nine months before Dhar was arrested by counter-terrorism police. He later skipped bail and was thought to have travelled abroad to Syria with his wife and four children.
Siddhartha Dhar is seen holding an Islamic State flag during the Channel 4 documentary, Jihadis Next Door
Dhar is suspected of being the latest British face of IS propaganda. In January a video was released which is believed to have shown him overseeing the murder of five men.
The documentary also focuses on an extremist preacher called Abu Haleema and his friend Mohammed Shamsuddin. Haleema has links to a teen jihadi who wanted to carry out a beheading on Anzac Day in Australia, while Shamsuddin was an associate of Islamic cleric Anjem Choudary and joined a radical group after meeting hate preacher Omar Bakri.
The extremists are seen staging aggressive street protests - where they were often challenged by other Muslims - appearing in court, praying in front of an IS flag and arguing with police.
Dhar pictured in the Islamic State execution video in January
During the film Roberts shows the extremists an execution video to gauge their reaction. They are seen laughing and making jokes at first, but later add it is “horrific ... it’s a horrible way to die.”
Haleema is filmed explaining that homosexuality and adultery under strict Islamic law will be punished. Those found guilty ill be thrown off high buildings and stoned to death. When asked if people would watch it, he says, “of course”. He disagrees it would be gruesome, saying: “No, people like that kind of stuff, innit.”
Haleema goes on to say that the racism his family encountered when he was younger "builds up hatred inside of you".
Shamsuddin told the broadcaster that the British government did not want to examine its own foreign policy, "all it wants to do is look at Muslims. Condemn Muslims, target Muslims." He went on to warn that the UK would "face a backlash" as a result.
He said: "If you’re gonna suppress a people for so long, if you’re gonna suppress and suppress I mean it’s like a tinder box, it’s gonna explode.”
The film, made by production company Mentorn over two years, explores the status that joining the radical extremist group gives some young men.
Haleema is often recognised due to his video messages on social media and one young man, Abu Mattasim from Birmingham who has had his passport taken from him by police, says that “makes me feel very good”. When asked why, he answers: “Because it makes me feel important.”
When asked about the November 13 Paris attack in which 130 people were killed Haleema says if "you're going to kill other people's innocents", the same thing is going to happen to your country in return.
He dodges questions about his allegiance to IS. When asked whether the jihadi in the latest execution video is Dhar, he says "there is definitely a resemblance", but says he can't be sure without seeing his face.
He says Dhar is "more than a friend of mine, he's my Muslim brother", and "He's from the best of the best of the best."
Roberts said when the latest IS execution video emerged in January Shamsuddin sent him a text telling him he might “know the voice”, which he took to hint that Dhar was the man overseeing the murders in the video.