In 1940, Maintenance Unit No. 28 was the biggest chemical weapons reception and storage depot in the United Kingdom. Up to 46,000 individual chemical weapons were stored on the 200-hectare site and in the surrounding country lanes. Wholesale burning of chemical weapons took place there after the war. In 1960 the site was closed. Since then the underground tunnels there have been used to store cheese and alcohol and to grow mushrooms. The site also contains a toxic quarry lake, where weapons were tested. Known to locals as ‘The Blue Lagoon’, it is very alkaline, with many warning signs to deter people from swimming in it. Part of the site is occupied by the Health and Safety Laboratory.