The possibility of independent individuals or local groups actually having the money, time, energy and capability to actually defend green space and nature is rather low.
In fact I suspect that until a centralised network for conservation evolves it's more than likely a journey further into the abyss. Systemic change is needed and I don't mean (just) through the political party system and the introduction of new policy (such as a nature and wellbeing act). An independent network that connects e.g. ecological consultants, planning experts, lawyers, media and publicity experts to local groups/community members is required I would say. A network that provides advice and co-ordination on how to defend green spaces a the local/ specific level. In essence a kind of HQ from where local groups can be coordinated and go to for assistance. That way when it comes to getting people together for e.g. demonstration, petition signing or even occupation there could be an assembled pool of people to draw support from and give support too. Basically for things to change for nature conservation it will take more than policy changes it will take an effective conservation 'army' which is centralised and well coordinated.