Who threatens us most — peaceful campaigners or a private militia run by police chiefs? This is what the head of a police unit set up to monitor domestic extremism said in 2009. “I’ve never said — and we don’t see — that any environmentalist is going to or has committed any violent acts.” No one has yet produced a factual challenge to that conclusion. Yet every year a shadowy body spends most of its £5m ($8m) budget on countering a non-existent threat that officers call eco-terrorism. It looks to me like a state-sanctioned private militia, fighting public protest on behalf of corporations.