Until he was jailed last year on charges of soliciting murder and inciting racial hatred, a man known to the police of several countries as Abu Hamza al-Masri was the imam of the Finsbury Park Mosque. He was a conspicuous figure because, having lost the use of an eye and both hands in an exchange of views in Afghanistan, he sported an opaque eye plus a hook to theatrical effect. Not as nice as he looked, Abu Hamza was nonetheless unfailingly generous with his hospitality. Overnight guests at his mosque’s sleeping quarters have included Richard Reid, the man in whose honor we now all have to take off our shoes at the airport, and Zacarias Moussaoui, the missing team member of September 11, 2001.

What happened next was captured in a mobile phone video. It shows a dark-haired girl dressed in a red track suit top and black underwear with blood streaming from her face. As she tries to rise to her feet she is kicked and hit on the head with a concrete block. Armed and uniformed police stand by watching her being killed over several minutes. Many in the crowd hold up their phone cameras to record the scene. Nobody tries to help her as she is battered to death.