11 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.

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.

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.

[2] 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 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 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.

The Chain Home radar system reported incoming enemy aircraft for the first time and the No.

[10] The Luftwaffe waged a campaign against the Royal Air Force aimed at destroying Fighter Command.

[12] The prime minister, Winston Churchill, visited the bunker on 16 August 1940 and spoke the famous words "Never in the field of human conflict was so much owed, by so many, to so few".

11 Group was involved in providing air support for the Dieppe Raid (Operation Jubilee) on 19 August 1942.

11 Group moved to RAF Martlesham Heath on 14 April 1958 and Dowding unveiled a memorial[20] close to the entrance to the bunker, commemorating its role during the Battle of Britain.

[23] In July 2015, the Government pledged £1 million for the restoration of the bunker, and the construction of a new visitor centre above ground.