Among the cabinet members who never fled their cabinet rooms in 1940 was Winston Churchill, who kept his seat on the prime minister’s chair for another three weeks after a knifing in his office caused an evacuation.
Stretching for more than 100ft (35 metres) down an internal corridor, Churchill’s bunker is a vast, five-floor bunker hidden deep inside the Westminster complex.
The bunker is the smallest of 14 inner sanctums in the complex, and the most hidden – including inside rooms that seldom get used for VIPs or visitors.
Working out of a former dentist’s surgery, the bunker began construction during Churchill’s second term as prime minister and came to a standstill in the second world war, although its vital role in wartime preparations was rekindled after the war.
By the end of the war, the bunker’s stonewalled exit and stairs through the interior of the Cabinet War Rooms had caused an evacuation of 1,000 diplomats, military chiefs and diplomats to a nearby airfield, instead of a direct flight out of London.
The prime minister went to the Great Hall and escaped first time, and was reported to have taken shelter again in his office.
However, members of the cabinet evacuated in the next batch – so that one cabinet member received a call from a fellow cabinet member, saying: “Well, we’ve all just gone.”
The bunker had been declared off-limits to normal use in 2006, although regular visits are organised by the Imperial War Museum.
There are 60in wooden doors to a concealed toilet, and a water supply overhead. A large door on the first floor and another on the fourth floor that leads outside also opens out to the courtyard below.
Those in the cabinet room monitor the ground-level situation via a computer.
As Churchill was known to complain: “If they put Widdle in a bunker, he won’t be moving out of there again.”