Airfield defence during the Phoney War was in reality limited to anti-aircraft defence. During April 1940 there was a growing realisation of the threat posed by air landing and parachute troops. It was considered the best way to meet this threat was with maximum use of light automatics, covered by wire entanglements, to sweep the aerodrome with a heavy volume of fire, including AA guns being given a secondary ground defence role. It was recognised that a Station could not be defended from the inside, the light automatics had to be sited to cover the aerodrome and the outside approaches. Provisions for a mobile force of light automatics mounted on vehicles and a relief force was also considered necessary.
During the summer of 1940, Maj-Gen G.B.O Taylor, Inspector of Fortifications, was tasked with formulating a defence policy for airfields against the most likely form of attack. He laid out the probable nature and scale of attack as follows: