The grid ref. of Middle Pit is ST 4821 7054 which places it about 150m NW of the position shown by AditNow. I tried editing the position but can't get it any better.
If in doubt it's located within a circular area full of trees and surrounded by modern residences although there appears to be public access to it.
Looking at it on 'Where's the path?' there appears to be a building there surrounded by scaffolding and under conservation. Wonder how many years ago that was!
Yes, I'll have it - what is it?