National Trust Opens Fan Bay Plotting Room in Dover Cliffs to Public

“It was a Tutankhamun moment for a conflict archaeologist,” said Jon Barker, the excavation leader for the National Trust.

The discovery of a hidden World War II “brain” bunker, buried four metres deep within the white cliffs of Dover, is finally being shared with the public. For decades, the Fan Bay plotting room remained a secret, mothballed in 1957 and kept classified until 1981 due to its military significance, The Guardian reported.

Starting this Friday, visitors can access the site through guided National Trust tours via a hatch located in a field. This pioneering command center housed the first land-based computer-aided targeting system, a piece of technology that acted as the central nervous system for a gun battery tasked with defending the Dover straits and attacking German vessels in the English Channel.

Churchill’s rapid defense mandate

The existence of the bunker and the artillery it controlled can be traced directly to the urgency of Winston Churchill’s leadership during the early stages of the conflict. Following his famous “fight them on the beaches” speech, Churchill visited the Kent coast and observed enemy ships passing through the straits of Dover without challenge.

At the time, Dover was a primary frontline target, facing constant bombardment from enemy guns stationed in occupied France. Churchill responded with a direct demand for technological superiority and rapid fortification.

Depositphotos stock white cliffs dover national trust

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,” according to The Guardian.

The speed of the construction reflects the high stakes of the era. Churchill demanded weekly updates on the progress of Dover’s defenses, and the guns were operational within 100 days. The plotting room bunker was completed just 64 days after that.

“The guns were known around here as Churchill’s pets,” Barker said.

The rush to secure the coast left physical evidence behind. Barker noted that rough openings in the walls and floors for cabling suggest the equipment was often installed before the official drawings governing the layout were even available.

Westerham england august chartwell country house of winston churchill now part of national trust

A unique electromechanical computer

While popular culture often depicts plotting rooms as groups of personnel moving markers across a physical map, the reality at Fan Bay was far more sophisticated. The bunker housed a 1.8-metre-long electromechanical computer known as a fire direction table.

This machine was used to calculate the precise position of moving ships when shells impacted, allowing the system to send real-time firing instructions to gun crews. Because of its advanced nature, the computer was deliberately destroyed in 1957 to prevent it from falling into enemy hands.

“We tend to think of plotting tables as glamorous Wrens [members of the Women’s Royal Naval Service] pushing around markers on a map as they do in war films. But it’s not a map – it’s a really cutting edge electromechanical computer, and it is completely unique,” Barker said.

The discovery of the room has drawn comparisons to the eventual preservation of Bletchley Park, the famous codebreaking site in Buckinghamshire. Barker suggested that while the public was unaware of the bunker’s existence for years, it has now become part of the national consciousness as a “new hidden history.”

Preserving the human element

The National Trust has chosen to conserve the plotting room exactly as it was found rather than attempting a modern recreation. The site retains original traces of the people who worked there, including old newspapers on the floor, discarded shoes, and official notices.

Even personal touches remain, such as chalked graffiti in a service tunnel reading “heroes fan hole Dodds and Petitt.” Barker suggested that Dodds and Petitt were likely the individuals responsible for the difficult task of hauling thick cabling through uncomfortable tunnels.

Because official records regarding the specific operators of the machine are scant, the National Trust is seeking help from the public. Barker is attempting to make contact with anyone whose family members may have served at Fan Bay to better understand the technical operation of the machine.

The identities of only a few operators are currently known, including Wallas Eaton, an actor who later appeared in the comedy series Up Pompeii, and a lance bombardier named WP Bryant. Barker noted that Bryant, a tailor by trade, “probably had a head for numbers.”

“There’s something very special about standing in a place that has changed so little since the people who worked here left,” Barker said.