I briefly stopped off in a little village called Cold Overton the other day.
In the corner of a field on the outskirts of the village, is an abandoned Royal Observer Corps underground monitoring post.
Some 1,500 of these posts were constructed all over the UK during the cold war, and manned by volunteers. They are all now either abandoned or demolished, the last ones to close were in 1991.
The post is basically a single room containing desks, blast monitoring equipment, bunks and a seperate WC, Power would have been provided by batteries, that could be charged by a generator above ground.
I’ve visited a few of these posts on my travels, but haven’t been to the Cold Overton post for around 12 years, on my last visit I took many photographs inside, but on this visit I wasn’t able to enter the bunker due to me working at the time and not suitably clothed for grubbing around in the dirt.
There’s more information about ROC posts on the Wiki for your perusal.
https://en.wikipedia.org/wiki/Royal_Observer_Corps_Monitoring_Post
I took a couple of exterior pics without getting too muddy.