The central roles played in the defence of Britain by the fighter squadrons and radar system were complemented by various ground elements - the Observer Corps, anti-aircraft guns, balloons and searchlights - which all contributed to the successful defeat of the Luftwaffe.

The Observer Corps, a network of civilian volunteers formed in 1925, had a vital role to play. The chain of coastal radar stations was very effective at plotting raids of incoming hostile aircraft, but it was blind once raiders crossed the coast. Inland, the whole responsibility of the accurate tracking of German aircraft rested with the Observer Corps. Enthusiastic, mostly unpaid and required to be on duty outdoors in all weathers, members were also largely self-taught in the crucial skills of aircraft recognition and height estimation. When the war broke out, there were 30,000 observers and 1,000 observation posts which were manned continuously. Information went first to an Observer Corps Centre and then straight to Group and Sector Operations Rooms. The system worked well when the weather was fine, but not when rain and low cloud were present.

Anti-Aircraft Command was not formed until 1 April 1939 and its late entry on the scene was to handicap it throughout the Battle. At the end of July 1940, it had only a half of the heavy and less than a third of the light anti-aircraft guns considered essential even before the Germans occupied France and the Low Countries. It was desirable to protect aircraft factories, airfields, ports, naval bases and industrial areas, but priority had to be given to the first of these. From 7 September, when the Germans launched their assault on London, many guns had to be switched immediately to its defence. The anti-aircraft forces were integrated with Fighter Command and operational control was in the hands of Air Chief Marshal Dowding who had an excellent working relationship with the head of AA Command, Lieutenant-General Sir Frederick Pile. Despite the problems, guns shot down approximately 300 German aircraft during the Battle.

Searchlights, which were operated with the gun defences, were active against German raids which flew over Britain on most nights from the beginning of June onwards. They were more plentiful than guns, nearly 4,000 being available towards the approved total of 4,128. In daylight they had the important function of reporting air activity to the gun operations rooms.

RAF Balloon Command was formed in November 1938 to operate barrage balloons over the most vulnerable targets. Expansion was rapid so that, by the end of July 1940, 1,466 were in service, 450 of which were required for the defence of London. The main aim of balloons was to force German aircraft to fly higher thereby reducing bombing accuracy and thus bring them within range of heavy anti-aircraft guns. Balloons were particularly effective against dive bombers.