Do you mean 'at all' or which British citizen he is? Why would not knowing stop the Brits from publishing something? Being void of the facts has never stopped them in the past.
There isn't even any evidence that he is "British". Some believe the British voice in the video was a mere voiceover, and not the voice of the man in the video.
So now ISIS is doing voice-overs as well? How long before they win all the prizes on 'The Price is Right' or get a guest spot on 'Celebrity Squares'? Pretty soon the Titanic is going to be an Icelandic ship as the Brits never fuk anything up. Sooner or later liars end up with no friends. This isn't the era where secrets can be kept and the world run on lies..