Inside Churchill's secret bunker, deeper than the Cabinet War Rooms

A new set of tours offers the public a rare opportunity to visit London's Down Street station, an abandoned tube station in Mayfair which played an important role in World War II

(CNN) — Some 73 feet below the traffic and bustle of London's Piccadilly lies a silent warren of corridors and pitch-black rooms, rarely seen, rarely visited, but which played a vital role in the course of 20th-century history.

Now, the opportunity has come round again to slip behind the door of the abandoned Dover Street Tube station and descend by torchlight into the World War II hideaway from which campaigns such as the D-Day landings and the Dunkirk evacuation were coordinated.

Britain's Prime Minister Winston Churchill sheltered here -- in secret -- in November and December 1940, when the German bombing campaign known as The Blitz was at its height, and a team of 40 staff worked here day and night on the war effort.