After World War II, a new line of division sprang up between the West led by the USA and Communist countries led by the Soviet Union. News reports of atrocities committed by communist leaders, as well as fears of a nuclear war, contributed to the sense of hysteria about Communists in the 1950s known as The Red Scare.
The term "Reds" comes from the flag of the Communist International, which was pure red.
Wiltshire is one of the larger counties in southern England. It takes its name from the town of Wilton on the river Wylye. The administrative center is Salisbury.
Wiltshire is home to numerous British military units, including army regiments stationed around Salisbury Plain. The airfield in question is likely to be one of the big Royal Air Force bases, such as Boscombe Down or Lyneham.
A pillar-box was a term for a post box.