That's great. Adding a little bit of history to pre-history. I've come across WW2 gun enplacements at several hillforts but nothing like this...

I've climbed into an abandoned ROC Nuclear bunker near where I live. I expected it to be piled high with cases of tinned pineapple, spam, crates of whisky and stacks of vintage jazz mags. Unfortunately it wasn't but still had equipment, charts, vintage telephone and furniture in it. Funnily enough there is an early Iron Age Hillfort just a hundred yards above it!

On a slightly more personal and poignant note... When over in Arran last month we tramped down to visit The Black Cave site at Bennan Head. On the way down we looked around a closed-up, derelict farm cottage and found the place had loads of signatures and drawings on the wall plaster and on some of the white painted equipment.
They were from WW2 Women's Land Army girls and the occasional bloke. Most had dates, some had drawings, some had their home addresses. During those years my mum was a munitions girl in a bomb factory near Kilmarnock and still gets a tiny pension for her bomb making. Some of her friends got blown up working there. I thought how lucky the Land Girls were to avoid the munitions work and spend the War out in beautiful places like Arran. It was a bit moving reading their inscriptions. It felt very close and personal. Here's a few from my Flickr account.

http://flic.kr/p/acX1RD

http://flic.kr/p/acX1S4

http://flic.kr/p/acX1Sa

This round barrow has a cold war ROC bunker built into it -

http://www.themodernantiquarian.com/site/8258/burgh_top_3.html

-Chris

The Broad Havens cliff fort, south of Aberdeen, has a WW2 gun emplacement.

http://www.themodernantiquarian.com/site/13798/broad_havens.html