Discovered on the grounds of a Norwich mansion in 2012, the station is thought to be one of 32 built during the Second World War in preparation for a German invasion.

David Evennett, Heritage Minister, said: "This underground wireless station is a rare and unusual example of our Second World War heritage and deserves to be protected.

“It is a reminder too of the often forgotten role so many civilians played in the war effort, often acting in secret and undercover."

Only 12 of Churchill’s stations have been found, though the Norwich structure is one of the most intact discovered so far.

The station features a fake bookcase and an escape tunnel, and was given heritage protection on the advice of Historic England.

Once a monument has been scheduled, developers require permission from the secretary of state before making any alterations.

Historic England manages this consent on behalf of the government.

Tony Calladine, Designation Team Leader at Historic England, added: “This amazing place that has survived intact played a highly secret but vitally important role in preparing us for a feared invasion during the Second World War.

“Because so much information about the stations was either hidden or destroyed, this small but significant dugout has great potential to teach us about a relatively little known area of our 20^th-century military history.”