They were normally setup by the people who dropped them off, its quite rare that people built them themselves. Incidently the name Anderson Shelter was named after the home secretary during WW2.

Thanks im here all week

I used to be obsessed with war and things when younger (average boy)...I could never grasp how one of these shelters would survive a bomb blast, direct or otherwise

The Anderson shelter was designed in 1938 by William Paterson and Oscar Carl (Karl) Kerrison in response to a request from the Home Office. It was named after Sir John Anderson, then Lord Privy Seal with special responsibility for preparing air-raid precautions immediately prior to the outbreak of World War II, and it was he who then initiated the development of the shelter. After evaluation by Dr David Anderson, Bertram Lawrence Hurst, and Sir Henry Jupp, of the Institution of Civil Engineers, the design was released for production.

Anderson shelters were designed to accommodate up to six people. The main principle of protection was based on curved and straight galvanised corrugated steel panels. Six curved panels were bolted together at the top, so forming the main body of the shelter, three straight sheets on either side, and two more straight panels were fixed to each end, one containing the door — a total of fourteen panels. A small drainage sump was often incorporated in the floor to collect rainwater seeping into the shelter. The shelters were 6 ft (1.8 m) high, 4 ft 6 in (1.4 m) wide, and 6 ft 6 in (2 m) long. They were buried 4 ft (1.2 m) deep in the soil and then covered with a minimum of 15 in (0.4 m) of soil above the roof. The earth banks could be planted with vegetables and flowers, that at times could be quite an appealing sight and in this way would become the subject of competitions of the best-planted shelter among householders in the neighbourhood. The internal fitting out of the shelter was left to the owner and so there were wide variations in comfort.

Anderson shelters were issued free to all householders who earned less than £250 a year, and those with a higher income were charged £7. 150,000 shelters of this type were distributed from February 1939 to the outbreak of war. During the war a further 2.1 million were erected.

At the end of the war in Europe, households who had received an Anderson shelter were expected to remove their shelters and local authorities began the task of reclaiming the corrugated iron. Householders who wished to keep their Anderson shelter (or more likely the valuable metal) could pay a nominal fee.[citations needed]

Because of the large number made and their robustness, many Anderson shelters still survive. Many were dug up after the war and converted into storage sheds for use in gardens and allotments.[7]