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The whole defence system of Fighter Command in 1940 was based on radar. The experiments had been successful. The new device worked. There were some 32 Chain Home radar stations, each involving 350 foot steel lattice masts, side by side, with 250 foot wooden masts. These were complemented by the Chain Home Low stations which had been developed by army scientists to detect aircraft flying at low altitude. On the steel masts were the radar devices sending out the pulse signals which got reflected from incoming aircraft. These reflections were picked up on the apparatus on the wooden masts. In their hut below, Airmen and WAAFs, known as Clerks-Special Duties, watched their cathode ray screens for the tell tale blips generated by incoming aircraft. Each such station was connected by landline, laid specially by the GPO to Bentley Priory. There, the signals came into a filter room designed to weed out false messages. Having got through that, the signal went on to the control room where a set of WAAFs, circulated around a very large scale map of Britain. There, they used the signals to place small blocks of wood representing the aircraft, red for the Germans which they called Bandits and black for ours. Above all this was a platform on which Dowding and his staff could watch the proceedings, as the WAAFs pushed the markers around.

Another important ancillary part of the organisation was played by the Observer Corps. With its 30,000 strong membership, spread amongst the one thousand observer posts dotted around the country, they fed their sightings of aircraft, enemy and friendly, through to their headquarters and from that to Bentley Priory. Each Observer Corps post was equipped with tin hats, apparatus for measuring the height of aircraft, telephones which connected them with the system, and, most important of all, tea making apparatus. The Observer Corps role was to keep track of aircraft over land. Radar only observed over the sea, pointing outward from the coast.

All this information which came into Bentley Priory was disseminated onwards to the four Groups. Each Group had a similar setup with WAAFs pushing markers around a map of their area. Executive responsibility for instituting action was held at Group level. The Group Commander decided which squadrons to send up, in what number, and which should be held in reserve. He actually fought the battle. It was on his skill and judgement that the outcome and confrontation with the enemy would depend. Each Group had its sector stations. These had the controllers who were in direct contact with the squadrons. They remained in touch with them after take off, giving them interception courses to fly which were marked on the Sector plotting tables. This is how Fighter Command was to operate throughout the battle. Its operations were invariably in response to what the radar was showing, which was plotted at HQ Control and then at Group Control. The whole thing worked like a coordinated machine. At the time, the system was absolutely unique, there was nothing else like it. It was to play a vital part in the battle.