Anderson shelters were a type of air raid shelter used in England during World War II. During the bombing of London, many existing structures were used as shelters, including basements and subway tunnels. However, the Home Office wanted something smaller that could be built by home-owners for small-scale use. While various designs were put into use, the most popular were the Anderson shelters.
Named after Sir John Anderson, the Lord Privy Seal (who also happened to have been given the responsibility for preparing air-raid precautions), the shelter was actually designed by engineers William Paterson and Oscar Carl Kerrison in 1938. The Anderson Shelter was a simple hut made of heavy corrugated iron panels, said to fit six people; they were specifically intended for use during the air raids, and had no conveniences upon installation. Most homeowners added benches or later, as the Luftwaffe started night bombings, cots. Some Anderson shelters were wired for electricity, included sump pumps for drainage, or were fitted with custom-built furniture, as their owners' pocket books allowed.
England geared up to provide as many citizens with Anderson shelters as possible, providing shelters free to families that earned less than £5 a week, and at a discounted price to those with higher incomes. Due to these governmental efforts, 1.5 million shelters were in place before England entered the war. By the time the Blitz began this number had increased to 2.5 million. The shelters were placed outdoors, in back gardens for the most part, and buried 1.2 m deep in the ground and then covered with at least a half meter of soil.
As you might imagine, the shelters were cramped -- 1.8 m in height, 1.4 m wide, and 2 m long. In addition, they were generally cold in the winter and often damp -- and in some cases, flooded. As the air raids became more common and started happening late at night, people became more reluctant to use the shelters every time the sirens went off, and a 1940 census found that the majority of people were not taking shelter during the raids. Because of this, and the fact than many Londoners did not have gardens, the Morrison shelter was introduced. This was an indoor shelter that was essentially a bed installed under a heavy table.
After the war the government undertook a buy-back project to reclaim the iron in the shelters. Citizens who wished to keep their shelters had to pay a small fee, but many elected to do so, and many shelters remained as tool sheds or forgotten hillocks in the back garden. Today surviving Anderson shelters can still be found, but they are becoming rare enough to be the object of preservation campaigns.