If an invasion took place, the Army and Navy had arrangements in place to deny military and naval facilities to the enemy and the RAF also put in place arrangements to deny the use of aerodromes and facilities for aircraft. It was recognised that carrying out a systematic series of demolitions while fighting to the last would be difficult!
In May 1940 Bomber Command issued instructions of measures to be taken if abandonment of a station became necessary:
The pumping mechanisms of aviation and motor transport fuel were to be destroyed with a hammer. Petrol in tins was to be set a light. Oil tanks were to be drained. If possible, bombs or explosives were to be put in place to demolish bulk petrol installations.
Vehicles and aircraft that could not be removed were to be destroyed.
Uniforms in store were to be burnt.
Food was to be contaminated.
Communications, lighting and water infrastructure to be made useless.
Orders for demolition could be given by A.O.C., G.O.C. or the Station Commander on his own authority if communication had been cut and the airfield was in imminent danger of capture.
In 1941, No 11 Group RAF made arrangements for the evacuation of certain forward Fighter aerodromes. Martlesham in Suffolk was one of these aerodromes and was to partially evacuate to Debden or Castle Camps. The objective of the evacuation was to allow more effective operations to be continued against the enemy from more remote aerodromes. An evacuation could be ordered two to three weeks before an invasion materialized. Although if a forward airfield was evacuated a guard remained to defend it to the last, arrangements were put in place to deny the runway to the enemy by demolition with Canadian Pipe Mines. By 1943 arrangements had been made at further airfields, some under construction, within 10 miles of the coast for the demolition of the runways. There were three methods of runway denial:
Canadian Pipe Mine – by driving pipes into the ground at 25 ft intervals in a line. In Suffolk, Martlesham, Debach, Woodbridge and Leiston were to be denied to the enemy by Canadian Pipe mines. The pipes were to be laid but not charged with explosives.
Mole Plough Method – ploughing in and installation of an explosive charge, with a 50 ft gap between charges in line. Charges were contained in 50 ft x 1 ½ inch rubberised tube. In Suffolk, Ipswich and Butley were to be denied to the enemy by the mole plough method.
Mine Method - Laying approx 250 AL No I Mark mines per 1,000 yds square of runway to provide a quick and effective method of temporary denying an airfield to the enemy. In Suffolk, Halesworth was issued with mines.