I did an ATC camp there in about 1967. Remember doing rifle drill in the pouring rain.
There was a lot of stuff underground, 6 levels i think. We only went down 2 levels.
According to wiki:-
The only surviving surface features of the site are the guardhouse, which has been refurbished, the generator building and a small blockhouse that doubles as an emergency exit for the bunker. The bunker too remains intact and is used by a private company for data storage.[3]
I didn't see the guardhouse when I went past today.