Churchill's Secret Fan Bay Bunker Opens Inside Dover's White Cliffs

A Second World War command bunker buried four metres deep in the white cliffs of Dover opens to the public on Friday. The Fan Bay plotting room, ordered by Winston Churchill, housed the first land-based computer-aided targeting system used in wartime Britain.

Jon Stewart, who led the excavation for the National Trust, said the concrete-encased room acted as a "brain" for a gun battery that defended Dover and attacked German ships in the Channel. The bunker was secretly mothballed in 1957 and remained classified until 1981 because of its military importance. Stewart was the first person to re-enter it when it was rediscovered in 2017.

"It was a Tutankhamun moment for a conflict archaeologist," Stewart said. "We had done all this research on the people who had served there, and then suddenly you're standing in their office. It was an exciting moment."

Why did Churchill build it?

The installation traces directly to the prime minister. Soon after his "fight them on the beaches" speech, Churchill visited the Kent coast and was alarmed to see enemy ships passing through the strait of Dover unchallenged. Dover was simultaneously under regular bombardment from German guns in occupied France.

In a July 1940 memo Churchill wrote: "We have to fight for command of the straits by artillery, to destroy the enemy batteries and fortify our own." He demanded the most advanced technology available and weekly progress updates. The guns were ready within 100 days. The plotting room bunker followed 64 days later.

"The guns were known around here as Churchill's pets," Stewart said. Rough openings cut through walls and floors for cabling still show the urgency. Contemporary accounts describe equipment installed before the layout drawings existed.

What was the machine inside?

The plotting room housed a 1.8-metre-long electromechanical computer called a fire direction table. It calculated the positions of moving ships when shells hit and sent firing instructions to gun crews. Up to 10 people worked there at a time. The computer was deliberately destroyed in 1957 to prevent it falling into enemy hands.

Stewart compared the find to the 1990s rescue of Bletchley Park, the Buckinghamshire codebreaking site. "We didn't know about it then, but now it's all part of our national consciousness," he said. "The plotting room is a new hidden history."

"We tend to think of plotting tables as glamorous Wrens pushing around markers on a map as they do in war films," he added. "But it's not a map – it's a really cutting edge electromechanical computer, and it is completely unique."

Who operated it?

The identities of only a handful of operators survive. They include Wallas Eaton, an actor who later played Senator Ludicrus Sextus in the TV comedy Up Pompeii alongside Frankie Howerd. Lance bombardier WP Bryant was also recorded as a plotter. "He was a tailor so he probably had a head for numbers," Stewart said.

Stewart wants to reach families of Fan Bay veterans. "What we know about it is based on a manual and ghost markings on the floor," he said. "I would really love to hear if anybody knows if their family members served at Fan Bay because the records are scant."

What will visitors see?

The National Trust will run guided tours through a hatch in a field. The room is preserved exactly as the excavation team found it, with old newspapers, shoes and official notices still on site. Chalked graffiti in one service tunnel reads "heroes fan hole Dodds and Petitt" — men Stewart believes installed the bunker's cables.

"They were probably self-appointed heroes responsible for marshalling horrible thick cable through particularly uncomfortable tunnels," he said.

"There's something very special about standing in a place that has changed so little since the people who worked here left," Stewart said. "Rather than recreate the past, we've carefully conserved the plotting room so visitors can experience it much as we found it, with all the marks of its history still visible. It's a rare opportunity to discover a completely different side of the white cliffs."