A Cold War nuclear bunker has been rediscovered underneath a centuries-old castle after being forgotten for 57 years.
The bunker was decommissioned and sealed in 1968 and was lost until an archaeological dig by English Heritage successfully uncovered its location.
In the event of a nuclear war, the space would have been staffed by volunteers from the Royal Observer Corps (ROC).
It is one of 1,500 underground observation posts built across Britain, each planned to protect three ROC volunteers who would have helped map where Soviet nuclear bombs had exploded and packed with rations for occupants to last about two weeks.
The exact location of the ROC post at Scarborough Castle in North Yorkshire had been a mystery since its closure, with websites pointing to it being buried somewhere between the castle and the North Sea.
The bunker measures just 15ft long and 7ft wide and is just tall enough to stand in.
It sits within the grounds of Scarborough Castle, a former medieval royal fortress on the east Yorkshire coast.
Kevin Booth, of English Heritage, said the secret bunkers were placed across the country, though most people were oblivious to their existence.
Archaeologists uncovered a Cold War nuclear bunker underneath a centuries-old castle
The bunker was found in the grounds of Scarborough Castle, a former medieval royal fortress on the east Yorkshire coast
He said: ‘Wherever you lived in Britain you were probably no more than a few miles from an ROC post.
‘Yet few people knew they existed.
‘It seems strange to have a Cold War bunker built inside Scarborough Castle, but in many ways, it is a perfect location.
‘This headland has been an observation post for thousands of years, from a Bronze Age settlement to a Roman signal station, medieval castle, WWI gun battery and, here, a 1960s concrete bunker watching for Armageddon.
‘We wanted to pinpoint it and see if we could reopen it and see what was inside.
‘Old mapping gives a sense of where it might be, but it really comes down to survey, looking under the ground with radar to find the big black blob that is a concrete structure.’
The bunker would have had a bomb indicator, which would have measured pressure waves in the event of explosions.
A pinhole camera would have been fitted on the top of the bunker which would have recorded the blasts.
The ROC post in Scarborough only operated for a few years, and was capped with concrete in 1968 as the nuclear threat at the time slowly reduced.
A camera has revealed it has since filled up with about six-feet of water in it.
Mr Booth hoped it could eventually be emptied and, when safe, people could take a step into the post for the first time in decades.
A picture showed what the inside of the bunker may have looked like before it was decomissioned
‘We’re getting inklings of some interesting survival down there,’ he said.
‘The wooden door that I’m looking down this shaft at, it’s solid, you can tap on it despite it being flooded for 60 years.
‘We’re finding a physical connection with the memories of the ROC, who tell me about these spaces, who tell me that they’re cold, who tell me they used to get fish and chips in instead of eating the rations.’
‘For English Heritage, it’s not only completing the story of Scarborough Castle, we’re completing the story of the Cold War and the way Britain was trying to deal with that threat.’
Lead archaeologist John said: ‘We knew where to start the excavations, because they are fairly modern features.
So we know there is historic records and there is actually one historic photograph which shows the site as it was just before it was demolished and cleared away.
‘We also redid some geophysics across the area, which picked up the outline of the post and the disturbance areas for the bunker itself.
‘So that allowed us to re-geolocate the site and put pegs in the grounds so we knew where the bunker was and the features on to’p of the bunker, so we could come in and then do target excavation.’
Helen Featherstone of The National Lottery Heritage Fund, added: ‘It’s really exciting that this lost bunker has been uncovered by the team working on this project marking 100 years of the Royal Observer Corps.
‘This find builds on our understanding of their story and shines a spotlight on their important work protecting the UK.
‘The project has been made possible thanks to money raised by National Lottery players, and I’m sure that they will be thrilled to know that they have played a role in this discovery.’