Who’d be a traffic warden, eh? The answer, it would seem, is any number of immigrants willing to be paid £7 an hour to be verbally abused, physically attacked and generally despised by the great British public. And Olly Lambert, writer-director of Channel 4’s well-made and informative Cutting Edge documentary, Confessions of a Traffic Warden, says that although his original intention was to find out about the people beneath the uniforms, what he actually discovered was the hair-trigger vileness of Londoners beneath a badly scuffed veneer of civilised behaviour.