Orford Ness may have been in the ownership of the National Trust and open to the public for the last 30 years, but there is still an air of mystery about the former top secret weapons testing centre.

Much of the site remains out of bounds to visitors - and some of the most iconic buildings remain far away from prying eyes.

East Anglian Daily Times: The pagodas at Orfordness are far away from the tourist trails.The pagodas at Orfordness are far away from the tourist trails. (Image: Paul Geater)

So the opportunity to get close to the most secret of all the installations on the former base couldn't be resisted.

And while the pagodas that were used to test the casings of Britain's atomic bombs are unlikely to ever be opened to the public, there was a chance to get a glimpse of the work that is being done to record and survey them.

East Anglian Daily Times: Jon Bedford from Heritage England with a drone and robot dog outside the pagoda.Jon Bedford from Heritage England with a drone and robot dog outside the pagoda. (Image: Paul Geater)

The most extraordinary kit is a team of robot dogs and drones that are being used to film and survey the buildings - possibly allowing the eventual creation of a virtual reality tour.

I'd seen robot dogs like this on television before and always thought they were gimmicks - an expensive toy.

But Russell Clement, general manager of the site for the National Trust said they were vital to the work.

East Anglian Daily Times: Russell Clement and Matt Wilson at Orfordness.Russell Clement and Matt Wilson at Orfordness. (Image: Paul Geater)

He said: "They can get into buildings like the pagodas which are too dangerous for people to go in and photograph and take survey measurements in great detail.

"They can climb up shingle banks that are inaccessible to wheels or caterpillars - they are absolutely vital."

Two robot dogs - and they are referred to as 'dogs' by the team - are surveying the pagodas that date from the 1950s.

East Anglian Daily Times: The Orfordness pagodas are the symbol of the place and are visible from the village.The Orfordness pagodas are the symbol of the place and are visible from the village. (Image: Paul Geater)

They were designed to test the casings of atomic bombs - and their exact construction details remain covered by the Official Secrets Act.

Mr Clement said: "There were only seven ever built in the UK. Two here and five at Aldermaston (the nuclear research centre) and they are still in use."

As well as the 'dogs' the team also uses a pair of drones to survey the building.

One photographs and measures the outside of the buildings - while a smaller drone is able to record everything inside.

East Anglian Daily Times: The smaller drone can film inside the pagoda.The smaller drone can film inside the pagoda. (Image: Paul Geater)

They are operated by scientists and engineers in a project that is also supported by Heritage England.

Jon Bedford from Heritage England is responsible for one of the 'dogs' and the drones.

He said controlling them was very simple - and produced very clear information: "The problem isn't controlling them, it's maintaining them and fixing any issues!"

The National Trust acquired the site from the Ministry of Defence in 1993, but no measured surveys have been completed of the buildings before.

East Anglian Daily Times: It is not safe to get into the centre of the pagoda because the structure is deteriorating.It is not safe to get into the centre of the pagoda because the structure is deteriorating. (Image: Paul Geater)

As scheduled monuments, they have the same designation as Stonehenge or the Royal Burial Ground at Sutton Hoo.

“Historic England’s research into the buildings made us realise how significant they are, on a national and international scale,” says National Trust archaeologist, Angus Wainwright.

East Anglian Daily Times: Orfordness retains an air of mystery 30 years after it was taken over by the National Trust.Orfordness retains an air of mystery 30 years after it was taken over by the National Trust. (Image: Paul Geater)

“These are some of the few Cold War buildings that are on this monumental scale and visitable by the public.

“The buildings used to be quite safe so we could go in and out as much as we liked, but now they are getting more risky as the concrete decays. That’s why we are doing this survey in this remote way, without anyone going into the buildings."

East Anglian Daily Times: There are many buildings at Orfordness like this former laboratory that will never be open because of safety concerns.There are many buildings at Orfordness like this former laboratory that will never be open because of safety concerns. (Image: Paul Geater)

In the last few years, the pagodas have also become part of the National Trust’s ‘curated decay’ policy and have been left to nature, including the effects of Orford Ness’ exposed coastal location.

Matt Wilson from the National Trust said: "This area is changing all the time - we lost the lighthouse in 2020 because it was in danger of falling into the sea.

In the long term that could happen to these buildings - it probably won't be in our lifetime, it could be hundreds of years but we will have a detailed record of how they are now."