The Civil Defence Service was a civilian volunteer organisation in Great Britain during World War II. Established by the Home Office in 1935 as Air Raid Precautions (ARP), its name was officially changed to the Civil Defence Service (CD) in 1941. The Civil Defence Service included the ARP Wardens Service as well as firemen, fire watchers, rescue, first aid post and stretcher parties. Over 1.9 million people served within the CD and nearly 2,400 lost their lives to enemy action.

The Home Office (HO), also known as the Home Department, is a ministerial department of the Government of the United Kingdom. It is responsible for immigration, security, and law and order. As such, it is responsible for policing in England and Wales, fire and rescue services in England, Border Force, visas and immigration, and the Security Service (MI5). It is also in charge of government policy on security-related issues such as drugs, counterterrorism, and immigration. It was formerly responsible for His Majesty's Prison Service and the National Probation Service, but these have been transferred to the Ministry of Justice.