"Muslim killers off our streets,” was the chant that rang out through Angry, White and Proud (Channel 4) as bands of aggressive men paraded on the streets of England, a fairly lethal look in many of their eyes. In a week where so much has been written about extremism following the terrorist murders in Paris, sitting down to watch a film about men whose response to the threat of mindless violence is nothing more than an alternative brand of mindless violence was always going to be unpleasant. And so it proved.