What do we know about the man behind the mask in latest IS film?

The British-sounding man who appears in the latest IS propaganda video.

Is Siddhartha Dhar, a former bouncy castle salesman from London, the masked man who has become the new face of so-called Islamic State?

His sister says "definitely not", some experts say "probably not", the authorities say "possibly not".

But despite multiple media claims to the contrary, the man behind the mask has not yet been identified. Sure, the intelligence agencies will have a good idea who he is – and no doubt the former Arsenal and Nirvana fan is high on the list, if not top - but after 48 hours of analysis no one can be sure.

I have spoken to some experts in the complex field of voice and facial recognition techniques who are adamant that the mysterious jihadist is not Dhar. One said we can’t even be sure whether the voice we hear in the film belongs to the man we see addressing the camera.

Dhar’s case was well known even before this video was released. He courted the limelight as a frequent contributor to news programmes. And once he eventually got to Syria, he became an IS propagandist, posting an image of himself online holding a rifle in one hand, his new-born baby in the other.

Last year, his sister gave ITV News an interview to appeal to him to return home. She told me: “It’s not him, if I can reach out to him to let him know that I want him to come back home, it doesn't need to be this way”.

It might seem unusual for such a high profile self-publicist to hide behind a mask during his biggest moment on the stage.

There are 800 British jihadists thought to be in Syria and Iraq. British spy services will be checking through their profiles to work out who it could be. But they haven’t concluded their investigation yet.

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