The Grange - Bunkers or Tunnels but unsafe

Historically important, should be listed. Could / should be a big tourist attraction for the village. Still find it amazing the Grange building wasn't listed as hugely significant in local history.

My son and his friends told me about a secret bunker they'd found near where we live. Very exciting stuff for a bunch of kids!! They took me to the Holy Cross site (near the entrance to the Grange off Gold Hill) and to the left in the woods before the nun's graveyard is a dell where they have started to fell and chop the trees down. In amongst the area are a number of holes (with significant drops into the tunnels/bunkers) If you were taking a stroll you could easily not see them and fall down those holes.
A bit further to the left is an entrance with concrete steps and an old wooden door has been taken off the entrance. Whether these are old war bunkers or the start of the mythical (!) tunnels that lead down to the greyhound I've no idea.
There is also a stone area with steps built around it with a statue of Mary on it.
My point is, as exciting as it is, the drops are dangerous for inquisitive children and walkers alike and are the developers doing anything to protect this area if it's of historical interest.
I called the local police but they said it was a council issue, but I'm wondering which parts of the site are public spaces and which are not, it's not very clear.
Can anyone help?
P.S I have lots of photos but don't think I can post them to this post