Battle of Britain Bunker

The Battle of Britain Bunker is an underground operations room at RAF Uxbridge, formerly used by No. 11 Group Fighter Command (later No.11 Group Air Defence of Great Britain) during the Second World War. Fighter aircraft operations were controlled from there throughout the War but most notably during the Battle of Britain and on D-Day. Today it is run by the Royal Air Force as a Force Development asset, but can also be visited by the general public as a heritage attraction with attached museum.

The Bunker is located at RAF Uxbridge, not far from Uxbridge town centre and Uxbridge Underground station.

Integrated Air Defence/The Dowding System
As the location of No. 10 Group RAF's Operations Room, The Battle of Britain Bunker was one of the key parts of the world's first Integrated Air Defence System. Often known as the "Dowding system" (after Air Chief Marshal Sir Hugh Dowding, Commander-in-Chief Fighter Command at the time of installation), the system linked Fighter Command with Anti-Aircraft Command, Barrage Balloon Command, the Observer Corps, Chain Home Radio Direction Finding (radar), and the intelligence services. Under the system, these organisations worked together for the first time in order to achieve one goal: the successful defence of the UK's airspace.

No.11 Group was an important part of the system for several reasons: Firstly, as one of four group headquarters, No.11 Group's Operations Controller was responsible for making key decisions that would affect the outcomes of aerial battles - how many fighter aircraft to scramble, which type of aircraft, which squadrons to use, when to scramble them, where to scramble them from, where to scramble them to, etc. Secondly and also due to its role as a group headquarters, No.11 Group was responsible for organising and coordinating the activities of seven sector stations at which its fighter squadrons were based - RAFs Kenley, North Weald, Debden, Biggin Hill, Tangmere, Hornchurch and Northolt. And thirdly, the Bunker and its Operations Room were the prototypes by which the other three group headquarters (No.10 Group, RAF Box; No.12 Group, RAF Watnall; No.13 Group, RAF Newcastle) were planned and constructed.

The Operations Room displayed various pieces of information in different ways, which the controller would then use in order to make his important decisions. The location of both enemy and friendly aircraft formations was displayed using numbered blocks on a map table. The current activities of No.11 Group's squadrons e.g. "At Standby", "Enemy Sighted", "Ordered to Land", etc. were displayed on a "tote" board using a series of lights. Current weather conditions at No.11 Group's sector stations were indicated with a system of coloured discs. And the passage of time was tracked using a coordinated system of clock and coloured indicators. All information was received from either Fighter Command headquarters or the sector stations via telephone.

Construction
Following excavations in 1938, the Bunker was constructed between February and August 1939 with the express intention of housing the No.11 Group (Fighter Command) Operations Room. Their previous Operations Room had been in an above ground building at RAF Uxbridge, but following the Munich Crisis of September 1938 and with the spectre of war on the horizon, the RAF began work on a protected underground alternative. The Bunker was built by Sir Robert McAlpine, a civilian company, but its construction was to remain top secret to avoid the plans falling into enemy hands.

The floor of the Bunker is located 60 ft below ground and is accessed by a staircase of over 70 steps. All utilities into and out of the building - electricity, water, telephone lines, sewage - are carried along pipes down this staircase. The walls, floor and ceiling are approximately 1 metre thick and are made of concrete with waterproof lining. The solid concrete walls and the approximately 30 ft of earth above the Bunker's ceiling meant that no bomb of the period could penetrate it.

A ventilation and air filtration system was installed to provide an air supply to the Operations Room staff. The original system still exists and functions well enough to continue ventilating the bunker.

The bunker finally became operational on 25 August 1939, just 10 days before the outbreak of the Second World War on 3 September.

Early Days: September 1939 – June 1940
On 1 September 1939 Nazi Germany invaded Poland. In response, the British military sent the Advanced Air Striking Force (10 squadrons of Fairey Battles) and the British Expeditionary Force, including an air component (Hurricanes, Lysanders, Gladiators and Blenheims), to France. Initially this air component was not under the control of No.11 Group at the Battle of Britain Bunker, however as the situation in Europe deteriorated No.11 Group was required to reinforce the BEF.

War was officially declared on 3 September 1939.

The Battle of Britain Bunker was involved in the war within the first week. On 6 September 1939 the Chain Home radar system reported incoming enemy aircraft for the first time and the No.11 Group Controller, working in the Bunker, despatched 56 Squadron and 74 Squadron to deal with the threat. Unfortunately the Spitfires of 74 Squadron mistook the Hurricanes of 56 Squadron for the enemy and shot two of them down, thus Fighter Command’s first losses of the war were as a result of friendly fire.

In April 1940 Air Vice-Marshal Keith Park was posted to No.11 Group as its Air Officer Commanding. Park would go on to distinguish himself in the Battle of Britain, devising the tactics and strategies for his controllers in the Bunker that would defeat the Luftwaffe and lead to the German’s naming him “Defender of London”.

Eventually, with the BEF on the verge of disaster, the decision was taken to evacuate them from the French channel port of Dunkirk. Between 26 May – 4 June 1940 the controllers in the Battle of Britain Bunker despatched fighter squadrons as part of Operation Dynamo, with the objective of defending the evacuees against air assault.

The Battle of Britain: 10 July – 31 October 1940
In advance of Operations Sealion (the Nazi invasion of the United Kingdom), the Luftwaffe waged a 16 week campaign against the Royal Air Force aimed at destroying Fighter Command. Of the four Fighter Command groups, No.11 Group (controlled from the Battle of Britain Bunker) saw the most action due its location in the South-East of England. Throughout the conflict Fighter Command destroyed 1733 enemy aircraft, of which No.11 Group was responsible for more than two-thirds.

Between 10 July – 11 August 1940 the Luftwaffe mainly concentrated on bombing ships in the English Channel and the ports of southern England. Then, on 12 August, they switched targets and attacked the Chain Home radar system. Serious damage to the RAF’s radar system (known as Radio Direction Finding in 1940) would have seriously limited the capabilities of their operations rooms (including No.11 Group’s in the Battle of Britain Bunker) to track and intercept enemy aircraft. Fortunately No.11 Group managed to fight the enemy off with only minor damage to the radar system.

On 13 August 1940 the Luftwaffe changed targets again, this time focusing on Fighter Command’s airfields. This caused serious concern within Fighter Command – controllers at the Group operations rooms (including in the Battle of Britain Bunker) would now be making decisions that not only affected their pilots in the air, but also their airfields on the ground.

The Luftwaffe’s targeting of Fighter Command airfields was more sustained than their previous assaults, continuing daily until 1 September. This period saw some of No.11 Group’s busiest and most successful days. The presence of AOC No.11 Group, AVM Keith Park, was in the Battle of Britain Bunker on several occasions during August and he hosted visits from the Prime Minister Winston Churchill and the King and Queen. At the end of his visit to the Battle of Britain Bunker on 16 August 1940, Churchill spoke the now famous words “Never in the field of human conflict was so much owed, by so many, to so few”. He said the phrase as he got into his car, close to the entrance of the Bunker, then repeated them in the House of Commons on 20 August.

The final phase of the Battle of Britain began on 1 September 1940, with the Luftwaffe changing targets for the final time and attacking London. Although the pressure was now off No.11 Group’s airfields, the month of September saw some of the fiercest fighting of the Battle, with Fighter Command struggling to defend the capital. As in August, AVM Park’s presence was required in the Battle of Bunker on several occasions, including 15 September when the Prime Minister visited again. Churchill would later write about 15 September 1940 in his memoirs, relating his conversation with Park about the progress of the day’s defensive operations, but also providing clues to the ferocity, complexity and desperation of the day’s fighting. At one point he writes about the moment at which “all of the bulbs glowed red”, referring to the squadron state boards in the Operations Room and indicating that every No.11 Group squadron was engaged in combat at the same time.

Incidentally, 15 September 1940 was to be the decisive day of the Battle, with Fighter Command shooting down 56 enemy aircraft for the loss of 26 of their own. Two days later Hitler postponed Operation Sealion indefinitely. However, Luftwaffe aircraft continued to attack the UK until the end of October, particularly at night, and thus the Battle of Britain Bunker remained busy throughout this period.

The Rest of the War: 1941–1945
In December 1940 AVM Park was replaced as AOC No.11 Group by his rival at No.12 Group during the Battle of Britain, AVM Sir Trafford Leigh-Mallory, who oversaw a thorough overhaul of the Operations Room within the Battle of Britain Bunker. The old plotting system of wooden markers and wooden croupier-style pushing sticks were replaced with metal plotting markers and magnetic sticks, and the old tote system of light-indicators was replaced with a slat-board system with hanging information. Around the same time the Battle of Britain Bunker had a royal box installed with views of the Operations Room. This was in advance of the formal visit of King George VI and Queen Elizabeth, even though both had been on informal visits in 1940.

In early 1941 No.11 Group was largely occupied with defending London against the Blitz, which had begun in September 1940 and coincided with the final stages of the Battle of Britain. However, once the Blitz had abated No.11 Group gradually began to focus on air operations over occupied Europe (although defensive operations over British airspace continued also). In August 1941 No.11 Group conducted its first fighter sweeps over enemy territory and these would continue throughout the war along with bomber escort missions. In August 1942 fighter operations during the Dieppe Raid were controlled from the Battle of Britain Bunker. In June 1944, fighter operations during Operation Overlord (the D-Day landings) were controlled from the Battle of Britain Bunker by the recently renamed No.11 Group Air Defence of Great Britain.

Post-war: 1945–1975
The Battle of Britain Bunker continued as the No.11 Group Operations Room until 1958 when the station was given over from Fighter Command to Technical Training Command. During this time the Ops Room was used to track aircraft during the early days of the Cold War.

In 1958, following the removal of Fighter Command from the station, Lord Dowding (formerly Air Chief Marshal Sir Hugh Dowding during the Battle of Britain) unveiled a memorial close to the entrance to the Battle of Britain Bunker, commemorating its role during the Battle of Britain and the fact that more than two-thirds of enemy aircraft shot down during the Battle were destroyed by No.11 Group. At the bottom of the memorial are recorded Churchill’s famous words: “Never in the field of human conflict was so much owed, by so many, to so few”, first spoken outside the Battle of Britain Bunker on 16 August 1940.

After 1958 the Battle of Britain Bunker became the home of the South-East Signals Centre, which in 1959 became the South-East Zone Telephone Switching Centre and then the South-East Communications Centre.

At the end of 1974 a decision was taken to restore the Plotting Room in the Bunker as it would have appeared during 1940. Work started in early 1975 and was completed in 9 months. The newly restored Plotting Room, designed to look exactly as it would have on 15 September 1940, Battle of Britain Day and one of the days on which Churchill visited the Battle of Britain Bunker, was officially reopened on 15 September 1975 by Air Chief-Marshal Sir Dennis Smallwood.

Heritage attraction: 1975 – today
Since 1975 the Royal Air Force has continued to run the Battle of Britain Bunker as a Force Development asset and public attraction. In 1985 responsibility for running the Bunker was given to Warrant Officer Chris Wren, the Station Transport Officer, as a secondary duty. Upon his retirement from the Royal Air Force in August 1994, Chris took on the job as a full-time Civil Servant until 28 February 2005. During his time he amassed a collection of approximately 5000 historic artefacts, allowing him to set up the museum in the controllers cabin and adjacent rooms together with a large display of photographs, prints and paintings within the museum, landings and corridors. He also installed a tape deck to play archive sound material through speakers in the museum and converted the former signals room in to a 50 seat briefing room to show relevant film footage. Above ground, he installed floodlights to illuminate the memorial unveiled by Lord Dowding in April 1958 and erected a flag pole to fly the RAF ensign

Since 2005 the Battle of Britain Bunker has remained in RAF hands, being managed by a series of professional curators with the help of volunteers. Chris Wren, though officially retired, continues to take tours into the Bunker along with colleagues.

The Plotting Room in the Bunker displays the squadrons and flights of Nos 602, 23(B), 213, 607, 46, 25, 249, 41, 603, 222, 605, 253, 503, 600 92, 72, 66 141(B), 257, 17, 73, 1(Can), 303, 229, 264(B) and 504. 1(Can) was a Canadian Sqn and 303 a Polish Squadron.

The Battle of Britain Bunker today
Today, the Battle of Britain Bunker houses the fully restored No.11 Group Operations Room, as it would have appeared on 15 September 1940 (otherwise known as Battle of Britain Day). It was on that day that the Prime Minister Winston Churchill visited the Bunker in order to watch the conduct of the day’s aerial fighting. In the event, Fighter Command destroyed 56 Luftwaffe aircraft for the loss of just 26 of their own, making it one of the most successful days of the Battle for the Royal Air Force. 15 September was later revealed to have been a truly significant day in the course of the Battle, as it was losses on the 15th that convinced Hitler an invasion of the UK could no longer be attempted. He postponed indefinitely the proposed invasion (Operation Sealion) two days later.

The Operations Room consists of a fully reconstructed plotting table with original Battle of Britain map and reconstructed aircraft markers; fully reconstructed tote board with squadron state indicators, weather indicators and original clock; original liaison dais; original royal box; and original controllers’ cabins.

The Bunker also houses the small museum with a collection of artefacts relevant to the Battle of Britain and the Royal Air Force in general. Artefacts include aircraft parts, weapons, medals, uniforms, photographs and documents amongst many others.