You started here with "associated with the environmental movement". That's not the same as everyone campaigning on a local issue who puts "environmental issues" into their big list of why some local development shouldn't happen: most of those people aren't associated with the environmental movement at all.
I guess my point is that I think the problem is nimbies, not environmentalists, and since I think we need a faster and cheaper planning system in the UK I think it's important to identify the actual problem. Getting the Campaign to Protect Rural England or whoever to produce a ranking of places by importance does nothing if we still have a system where local residents can raise objections about building on locations at the bottom of the ranking and it takes forever to push something through.
Sure, the environmentalism movement has sufficient independent organizations such that each of them can protest some site as environmentally sensitive while the others stay quiet. I'm sure some would conclude that this position of universally banning any human development everywhere is a pure accident and that distributed agreement to do so has no evidence of systematic coordination.
I can believe there is no systematic coordination across these organizations, but if I had to meet someone in San Francisco and I knew nothing about where and there was no way to coordinate, I think we'd both end up in front of the Ferry Building on the Embarcadero.