Grovely Woods?That's the one. Good work.
@wheelchairwarrier's earlier comments reminded me of a 'find' I made about 20 years ago when I was wandering around woodland not far from my parents home near Win Green in Wiltshire (grid reference ST927209).
I walked off the bridle path down a steep wooded bank and found a green door placed in the side of the ridge. It was about 6' high and partially concealed. There was a slight flow of air coming from within via small gap in the door. I assumed this meant there was another entrance.
I went back a few months later but couldn't find the correct location. My father reckoned there was some sort of 'installation' in the area but I'm not sure how he would have known.
In a completely unrelated incident much later I inadvertently landed my paraglider a little further down the ridge and nearly landed on an FFR Landy. It was well concealed and part of a section of 264 Signals (I think). They were using the high ridge as a repeater station for an exercise taking place, presumably, on the Plain.
Lots of old WW2 bunkers etc there