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 . History of the Battle of Britain Bunker . 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 Battle s ) 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 .