Two former nuclear bunkers, each about the size of a small caravan, have sold at auction for a total of £18,000.
Hawkshead bunker was constructed in October 1965
One of the underground monitoring posts, in Stannington, Northumberland, fetched £7,000 and another at Hawkshead, Cumbria, went under the hammer for £11,000 at the auction on Thursday.
As an architectural curiosity the bunkers, two of around 1,500 in the UK, are much sought after, but the story of their Cold War-era occupants is less well known.
The Royal Observer Corps (ROC) was a voluntary organisation, entrusted with the task of monitoring and recording a nuclear attack on the UK.
Its job was to find out how many nuclear bombs were falling, where they might land, and to track the radioactive dust - or fallout - thrown up by any explosions, as it drifted across the country.
Three volunteers would carry out their task from each bunker, using an array of equipment crammed into the small room.
If a nuclear bomb or bombs were dropped nearby they were required to measure the detonation power, as well as the movement of radioactive dust.
Some ROC equipment still remains inside the Stannington bunker
Using sirens, they could warn the public of an imminent air or missile attack, or approaching fallout.
Subterranea Britannica, a society devoted to the study and investigation of man-made and man-used underground places, has catalogued all of the bunkers and studied the role of the ROC.
According to society member John Smiles, the military used alert states to indicate the severity of the situation. These were "black" (no threat), "black special" (possible threat), "amber" (high state of readiness) and "red" (war).
He said: "Amber was reached at the height of the Cuban missile crisis. Fortunately, that situation went no further, although fingers were on triggers.
"In the event of a nuclear attack, the bunkers were only intended to be manned for a total of two weeks.
"If there had been a blast nearby, the volunteers inside would be protected and could monitor the situation from the shelter.
"However, they could be instructed to go outside the bunker and check the infrastructure, for example to find out if a road was blocked.
"Anyone sent outside the bunker sooner than two weeks after a detonation would most certainly be exposed to a fatal dose of radiation.
Volunteers were expected to measure the force of explosions
"But after that time, radiation levels would have dropped enough to allow them to go outside for a limited period of time, perhaps to seek out alternative shelter and supplies.
"And anyone they encountered would most likely be in a worse state than them, having not being sheltered from the worst of the radioactivity."
The monitoring posts at Stannington and Hawkshead, both built in the 60s, are both well preserved and still contain much of the original equipment used by the ROC.
Many of the other sites around the country are slightly the worse for wear, either demolished or wrecked.
Mr Smiles said: "Usually, they're very popular with local kids. It doesn't take long for them to get in and trash the place.
"In fact, it's not unknown for them to use some kind of industrial cutting equipment to get past the hatch.
"But Stannington in particular is probably one of the best preserved bunkers in the country.
"Looking at the Stannington photographs, you can see a circular dish on the wall - that's the mounting for the bomb power indicator. And the metal pipe running to the roof was used to measure radiation levels outside.
"There would also have been a radio, to talk to the command post, and a simple one-way telephone. That wouldn't be much use; you can probably imagine the kind of damage a nuclear explosion would do to telegraph poles and telephone wires."
All posts were issued with hand-operated sirens and maroons - a type of firework which makes loud bangs - for alerting the public.
Using the siren to sound the "red" warning (a rising and falling note) indicated an imminent air or missile attack and the "white" warning (a steady note), indicated "all clear".
With the approach of radioactive fallout the maroon would be used to sound the "black" warning - a series of three explosions at close set intervals.
Following re-organisation in the 1960s some of the bunkers were closed, and in 1991 it was decided by the Home Office & Ministry of Defence that the ROC would cease active training. The remaining underground posts were closed at the end of September that year.
The ROC's job is now carried out by computers - monitors positioned around the country, which can automatically detect and pinpoint any missile attacks, and monitor fallout and radiation levels.
This is perhaps for the best, speculates Mr Smiles.
He said: "A computer will do exactly what it's told following a nuclear strike, and won't be worrying about its family."