The Civil Defence Corps (CDC) was a civilian volunteer organisation established in Great Britain in 1949 to mobilise and take local control of the affected area in the aftermath of a major national emergency, principally envisaged as being a Cold War nuclear attack.

The Castle was also one of the sites for PYTHON, the plan for continuity of government in the event of nuclear war.

[3] The Civil Defence Corps was disbanded due to persistent shortages of volunteers which resulted from the widely-held belief that extensive damage which would be inflicted by hydrogen bombs in a nuclear war made it pointless to prepare for such a conflict.

The Civil Defence Corps initially inherited vehicles and equipment that had been stored since the end of the Second World War.

The Radiac operator would gather radiation level measurements that would be analysed together with wind patterns by the intelligence section.

Every industrial or commercial undertaking which employed two hundred or more people could form a civil defence unit to protect its own property and staff.

These units were organised in a similar way to the Civil Defence Corps, with Headquarters, Warden, Rescue, First Aid and Fire Guard Sections.