Even though it is Southwark, I suspect that most people using One Tree Hill are Lewisham residents.

It's not entirely clear from the maps what security measures are coming - replacing gates, but will they be locked up? If so, what arrangements for getting people out? Lighting the road up to the church would be a big improvement. Southwark Council also says here they will be improving the viewpoint area. Clearing some (not too many) trees (or pollarding) would open up some of the views, but improving the area so it is not just an underage bar/toilet can only help.

Southwark Council make it easy to respond to this. I wonder if another local council might take note.