Churchill War Rooms is not a reconstruction. The rooms you walk through today are the same rooms where Britain’s wartime leadership worked, argued, and made decisions while bombs fell on London above them.
The clocks on the walls, the pins in the maps, the scratch marks on Churchill’s chair, they are all original. When the lights were turned off in the Map Room on 16 August 1945, the staff left in a hurry.
When the doors reopened decades later, much of the bunker was exactly as they had left it.
The story of the War Rooms begins before the Second World War, in the late 1930s, when the threat of aerial bombing forced the British government to ask a simple question: where do you run a country from when the capital is under attack? The answer was not a purpose-built fortress in the countryside. It was a set of basement rooms beneath a government building in Whitehall, converted in a matter of weeks and kept secret for years.
This is the full history of how the Cabinet War Rooms were built, what happened inside them, and how they survived to become one of London’s most visited museums.
History
The Cabinet War Rooms were built between 1938 and 1939, converted from existing basement rooms beneath the Treasury building in Whitehall. The site was confirmed on 31 May 1938, and conversion work began immediately that summer. By September 1938, the rooms were ready for emergencies during the Munich Crisis. They became fully operational on 27 August 1939, one week before Britain declared war on Germany on 3 September.
The speed of the conversion was remarkable. In just a few months, workers cleared the basement rooms, sandbagged alcoves, replaced glass doors with teak, built brick partitions, installed telephone lines, and established a BBC broadcasting connection. Air locks and steel doors were added to defend against gas attack. The Map Room was manned and tested by the end of August 1938.
Here’s how the construction unfolded year by year:
31 May 1938
The basement beneath the Treasury building in Whitehall is confirmed as the site for an underground emergency headquarters. Its location, close to Downing Street and Parliament, makes it the practical choice.
June to August 1938
Conversion work begins immediately. Rooms are cleared, alcoves sandbagged, glass doors replaced with teak, brick partitions built, and telephone lines installed. A BBC broadcasting connection is established. The Map Room is manned and tested. Air locks and steel doors are fitted against gas attack.
September 1938
The rooms are ready for emergencies during the Munich Crisis. Britain and France agree to let Germany annex parts of Czechoslovakia, and war is narrowly avoided. The War Rooms stand by but are not yet needed.
27 August 1939
The Cabinet War Rooms become fully operational, one week before Britain declares war on Germany on 3 September 1939.
May 1940
Winston Churchill becomes Prime Minister. He walks into the Cabinet Room and reportedly says, “This is the room from which I will direct the war.”
29 July 1940
Churchill’s War Cabinet meets in the Cabinet Room for the first time. The defence of Britain from invasion is now being coordinated from underground.
11 September 1940
Churchill makes his first broadcast from the Cabinet War Rooms, warning Britons about the risk of invasion.
September 1940
A bomb narrowly misses the Cabinet War Rooms, leaving a crater near the Clive Steps outside the entrance. The near miss underscores how vulnerable the site really is.
December 1940
A reinforced concrete slab up to three metres thick is installed above the War Rooms. It can withstand a 500-pound bomb, but anything larger could still penetrate. Secrecy remains the primary defence.
July 1943
A reinforced concrete slab up to three metres thick is installed above the War Rooms. It can withstand a 500-pound bomb, but anything larger could still penetrate. Secrecy remains the primary defence.
28 March 1945
The final War Cabinet meeting is held in the underground Cabinet Room. The V-bomb threat to London has ended, and meetings return above ground.
16 August 1945
The lights are turned off in the Map Room for the first time in six years. Staff leave in a hurry. The war is over.
1948
The War Rooms are given the status of a historic site. Much of the complex is left as it was when the staff walked out in 1945.
4 April 1984
Prime Minister Margaret Thatcher opens the Cabinet War Rooms to the public in a ceremony attended by Churchill family members and former War Rooms staff. The museum is initially administered on behalf of the Department for the Environment.
1989
Responsibility for the museum is transferred to the Imperial War Museum.
2003
A major expansion adds a suite of rooms used as personal accommodation by Churchill, his wife, and close associates during the war. These rooms had been stripped of furnishings after 1945 and used for storage. The restoration costs £7.5 million.
2005
HM the Queen opens the Churchill Museum, a modern biographical exhibition exploring Churchill’s life and career. The site is renamed Churchill War Rooms.
The War Rooms were not built from scratch. They were adapted from existing government basement offices by construction teams working under the direction of the Office of Works. The location was chosen for a practical reason: it was close to Downing Street and Parliament, but discreet enough to avoid drawing attention.
Once operational, the complex was used by the War Cabinet, military chiefs, intelligence officers, and hundreds of support staff. Churchill’s War Cabinet met in the underground Cabinet Room 115 times during the war, most often during the Blitz and the later V-weapon attacks.
But the bunker was not just for senior leaders. Typists, switchboard operators, map plotters, clerks, and Royal Marines all worked shifts underground, keeping the complex running 24 hours a day for six years.
George Rance served as the Clerk and Custodian of the Cabinet War Rooms throughout the war, managing the day-to-day running of the complex and its staff.
The threat of aerial bombing forced the issue. By the late 1930s, it was clear that any future war would involve sustained bombing of London. The government needed a secure location where the War Cabinet and military commanders could meet and make decisions during air raids without interruption.
Moving the entire government out of London was considered but rejected. The War Cabinet needed to be close to Parliament, Downing Street, and the military headquarters in Whitehall. A central London site was essential, but it had to be underground and secret.
The basement beneath the Treasury building fitted the bill. It was in the right location, structurally solid enough to offer some protection, and could be converted quickly. The decision was driven by urgency, not elegance. These were not luxurious bunker rooms. They were cramped, poorly ventilated basement offices adapted for crisis use.
The War Rooms by the numbers
115
227 kg
557,000+
6 years
3 metres
thickness of the reinforced concrete slab
£7.5 million
The War Rooms were not built from the ground up. They were converted from existing basement rooms beneath the Treasury building on King Charles Street. This made the project fast but also imposed serious limitations. The rooms were small, the ceilings were low, and the corridors were narrow.
During the summer of 1938, workers cleared the basement, sandbagged vulnerable points, replaced fragile glass doors with solid teak, and built brick partitions to create separate functional rooms. Telephone lines were installed, a BBC broadcasting connection was set up, and air locks and steel doors were fitted to protect against gas attack.
The complex was designed around two core functions: a secure meeting place for the War Cabinet (the Cabinet Room) and a military information centre built around the Map Room, where intelligence was gathered, verified, and displayed for senior leaders.
Protection was a constant concern. In December 1940, after the Blitz exposed the vulnerability of the site, a reinforced concrete slab up to three metres thick was installed above the rooms.
Even that had limits. The museum notes that a direct hit from anything larger than a 500-pound (227 kg) bomb could have penetrated the building and destroyed everything below. Secrecy remained the best defence. Most people in London had no idea the complex existed.
Plan Your Visit
- Book Churchill War Room tickets online in advance to skip the line.
- Want to delve deeper into the history of WW2? Check our Churchill War Rooms tour options for guided and walking tours.
Life Underground
The War Rooms were not just a place for dramatic high-stakes meetings. For six years, hundreds of men and women spent thousands of hours working, eating, and sleeping in a cramped, airless basement with no natural light.
Working conditions
The complex ran 24 hours a day, seven days a week, from August 1939 to August 1945. Staff worked in shifts, and the atmosphere was one of constant, grinding routine punctuated by moments of crisis.
The air was stale. Ventilation was mechanical and noisy, but it never fully cleared the underground smell. There was no natural light, and the artificial lighting was on around the clock. Workers quickly lost track of time, day, and season.
To help staff cope, George Rance, the Clerk and Custodian, maintained weather indicator boards in the main corridor.
These told underground workers whether it was sunny, rainy, or overcast above ground. During air raids, Rance changed the indicator to “Windy” as a running joke that became a beloved tradition. Health was a concern.
To compensate for the lack of sunlight, staff had to strip to their underwear, put on protective goggles, and stand in front of portable sun lamps. Incidences of accidental “sunburn” were common. One staff member forgot to put on the goggles and nearly went blind.
The Dock: sleeping underground
Below the main level of the War Rooms, a sub-basement nicknamed “the Dock” provided sleeping quarters for staff who could not safely travel home during air raids. The Dock was deeply unpleasant.
The ceilings were so low that anyone taller than four feet had to stoop. There were no flushing toilets, only chemical ones. The ventilation system rattled throughout the night. Mice were common.
It was extremely dark, and staff needed torches to find their way to their bunks. Betty Green, personal secretary to General Ismay (Churchill’s chief military adviser), described the Dock as “revolting.” Many staff preferred to risk the journey home through an air raid rather than spend a night down there.
The people behind the operations
The War Rooms were not just Churchill and his generals. The complex depended on a small army of support staff who kept it running.
In Rooms 60 Right and 60A, switchboard operators handled communications and up to 11 typists worked simultaneously in the typing pool. Because photocopying equipment was rudimentary, every copy of meeting minutes had to be typed out by hand on Remington “noiseless” typewriters.
Map plotters in the Map Room worked in shifts to keep the wall maps updated with the latest intelligence on troop movements, convoy positions, and bombing targets.
The information they displayed was used directly by Churchill, the King, and the military chiefs. Royal Marines guarded the entrances.
Clerks managed the flow of documents. Cooks prepared meals in a tiny kitchen. The bunker was a functioning workplace, and the people who kept it running rarely get the recognition they deserve.
Key Rooms
The Cabinet Room
This is the room Churchill meant when he said, “This is the room from which I will direct the war.”
The War Cabinet met here 115 times during the conflict, with up to 20 people crammed around a table arranged in a square. Churchill sat at the head of the table. The three heads of the armed forces sat in the centre facing him.
Meetings could be tense, and the evidence is still visible: Churchill’s wooden chair still bears scratch marks left by his nails, wedding ring, and signet ring during heated discussions. The final War Cabinet meeting in this room took place on 28 March 1945, once the V-bomb threat to London had passed.
The Map Room
The Map Room was the nerve centre of the entire complex. Manned 24 hours a day from the moment the War Rooms opened, it was where intelligence was gathered, verified, and displayed on wall-mounted maps covered in pins and coloured threads.
The information assembled here was presented directly to the King, the Prime Minister, and the chiefs of the armed forces. Churchill spent the entirety of D-Day in this room, watching the progress of the Allied invasion. When the war ended on 16 August 1945, the Map Room staff left in a hurry.
The maps, pins, and documents were left exactly where they were. When IWM took over the site in the early 1980s, they found three sugar cubes hidden in a desk drawer, left behind by Wing Commander John Heagerty decades earlier. Those sugar cubes are still on display.
The Transatlantic Telephone Room
One of the most remarkable rooms in the complex was hidden even from most of the people who worked there. A converted broom closet housed a telephone connected to one of the most advanced communication systems of the war: SIGSALY.
Developed by Bell Telephone Laboratories in New York (in consultation with Alan Turing), SIGSALY digitised the human voice, mixed the signal with randomly generated noise, and transmitted it via radio waves across the Atlantic.
It was the world’s first digital secure speech system and a direct ancestor of modern encrypted communications.
The system went into service on 15 July 1943, connecting the War Rooms to the Pentagon. For the first time, Churchill could speak securely with President Roosevelt without fear of German interception. Previous phone calls between the two leaders had been monitored by censors who would cut the line if anything sensitive was mentioned.
The room was disguised. A sign on the door read “toilet” to discourage curious staff from entering.
Churchill’s Bedroom
Churchill had a small personal bedroom in the War Rooms, complete with a desk, a bed, and a chamber pot.
He used the room for work and occasionally for broadcasts, but he reportedly preferred sleeping above ground at the No. 10 Annexe (a fortified flat above the War Rooms) or at Downing Street itself.
Churchill was not someone who liked being underground. He tolerated the War Rooms as a necessity, but he was known to resist spending more time there than he had to.
The bedroom was functional, not comfortable, and it reflects the austere reality of the entire complex.
From Secret Bunker to Museum
The story of how the War Rooms survived is almost as remarkable as their wartime use.
When the lights went off in August 1945, there was no immediate plan for the site. The rooms were simply closed up. Unlike many wartime facilities that were stripped out and repurposed, much of the Cabinet War Rooms complex was left intact.
In 1948, the site was given the status of a historic site, which helped protect it from demolition or conversion.
For decades, the War Rooms sat quietly beneath Whitehall, largely forgotten by the public. In 1981, Prime Minister Margaret Thatcher decided the public should have access.
The Imperial War Museum took on the project, and on 4 April 1984, Thatcher opened the Cabinet War Rooms to visitors in a ceremony attended by Churchill family members and former War Rooms staff.
The initial museum covered the core wartime rooms. In 2003, a major expansion added a suite of rooms that had been used as personal accommodation by Churchill, his wife Clementine, and close associates during the war. These rooms had been stripped of furnishings after 1945 and used for government storage for decades. Restoring them cost £7.5 million, and the restored rooms opened to visitors in 2003.
In 2005, HM the Queen opened the Churchill Museum, a modern biographical exhibition exploring Churchill’s life from childhood to his post-war years.
The site was renamed Churchill War Rooms, combining the preserved wartime bunker with the new museum. Today it is one of the five branches of the Imperial War Museum and attracts over 557,000 visitors a year.
Did You Know?
Churchill’s chair still has his scratch marks
In the Cabinet Room, Churchill’s wooden chair still bears the marks he left during tense wartime meetings. The scratches on the left arm were made by his nails and wedding ring. The marks on the right arm came from his signet ring. They have been preserved exactly as he left them.
“Windy” meant bombs were falling
The weather indicator boards in the main corridor told underground staff what the weather was like above ground. During air raids, George Rance, the custodian, would change the indicator to “Windy” as a dark joke. Everyone underground knew what “Windy” really meant.
Sugar cubes from 1945 are still on display
When IWM took over the site in the early 1980s, three sugar cubes were discovered hidden in a desk drawer in the Map Room. They had been left behind by Wing Commander John Heagerty when the staff evacuated in August 1945. Sugar was strictly rationed during the war, making even a few cubes a prized possession.
The secret telephone room was disguised as a toilet
The Transatlantic Telephone Room, where Churchill spoke securely with Roosevelt using the SIGSALY system, was a converted broom closet. A sign on the door read “toilet” to keep curious staff from investigating. Most people working in the War Rooms had no idea the room existed.
A bomb landed just outside the entrance
In September 1940, a bomb narrowly missed the Cabinet War Rooms and left a crater near the Clive Steps, just metres from the entrance. The near miss was one of the reasons the reinforced concrete slab was installed three months later.
Staff risked air raids rather than sleep in the Dock
The sub-basement sleeping quarters were so unpleasant, with low ceilings, chemical toilets, mice, and constant noise from the ventilation system, that many staff chose to make the dangerous journey home through bombing raids rather than spend a night there.
The SIGSALY system helped start the digital revolution
The SIGSALY secure telephone system, developed with input from Alan Turing, was the world’s first digital encrypted voice communication system. It pioneered pulse-code modulation, a technology that underpins modern digital communications. Between 1943 and 1946, SIGSALY terminals conveyed over 3,000 high-level telephone conversations worldwide.
Churchill spent D-Day in the Map Room
On 6 June 1944, Churchill spent the entire day in the Map Room, watching the progress of the Allied invasion of Normandy as reports came in from the beaches. The room was staffed around the clock, but D-Day was one of its most intense moments.
Visiting Churchill War Rooms Today
Churchill War Rooms is now one of London’s most visited museums and a Tripadvisor Travellers’ Choice Award winner. Over 557,000 people visit each year, making it one of the top-rated attractions in Westminster.
Understanding the history of the War Rooms transforms your visit. Instead of just looking at old rooms behind glass, you will recognise the Cabinet Room where Churchill directed the war, the Map Room where D-Day was tracked in real time, and the tiny broom closet that housed one of the most advanced communication systems of the 20th century.
What you will experience
📜 Cabinet War Rooms: Walk through the preserved wartime rooms, left largely as they were in August 1945. See the Cabinet Room, Map Room, Churchill’s bedroom, and the Transatlantic Telephone Room.
🏛️ Churchill Museum: A modern biographical exhibition covering Churchill’s life from childhood through his military career, political career, wartime leadership, and post-war years. Interactive displays and personal artefacts bring his story to life.
Recommended Tours:
Planning Your Visit
→ Need more help planning? Check out Complete Churchill War Rooms Guide for information on what to see, opening hours, and practical tips for your visit.