NS4079 : Royal Observer Corps Monitoring Post, Alexandria
taken 13 years ago, near to Jamestown, West Dunbartonshire, Scotland

The pipe in the foreground would have supported the FSM (Fixed Survey Meter), an instrument for measuring levels of ionising radiation from fallout: NS4079 : Alexandria ROC Bunker: FSM mount.
The main structure contains an access shaft (now blocked), leading to the underground chamber from which the observers would monitor the various instruments: NS4079 : Alexandria ROC Bunker: access shaft. The structure also supported the Ground Zero Indicator, an instrument for recording the direction and elevation of a nuclear blast: NS4079 : Alexandria ROC Bunker: GZI mount.
In this view, part of Loch Lomond can be seen in the background, with Glen Finlas beyond it (directly behind the access shaft). The large building on the left, with the tall chimney, is NS3980 : Loch Lomond Distillery.
This ROC monitoring post — see Link and Link for a detailed description of these Cold War relics — was a master post. It is set in a field, on a west-facing slope, just downhill from a small square of woodland that contains the ruins of Northfield Cottage. At the foot of the slope is Northfield Road and the Dalmonach estate.
The Royal Observer corps was a civil defence organisation operating in the United Kingdom between 29 October 1925 and 31 December 1995.
During the cold war ROC monitoring posts were developed for monitoring fallout and radiation in the event of a nuclear attack. The operators hidden below would occasionally emerge to collected photographic film from a 4-axis parabolic camera mounted near the hatch, retreating below ground to develop it. A patch of darkening might have indicated the direction of an explosion. Once centally collated these observations would triangulate the site of an attack.
A variety of instruments would detect radiation and fallout levels, and the bunker itself used the earth to protect the volunteer observers, who had telephone and radio communications up the chain of command.
There were 1,563 of these posts constructed and one of the specialist groups researching the history of the ROC has mapped them all. See Link(there is a great deal of detailed information about the posts on the rest of that site)
See Linkfor background and a reconstruction of a working observation post.
There is a good history of the ROC on wikipedia at Linkand a charitable association for the welfare of the former volunteers at Link
