The Consortium of Local Authorities Special Programme (CLASP), was formed in 1957 by Local Authorities in England to develop a shared prefabricated system for the construction of school buildings. The resulting CLASP building system was initially developed by Charles Herbert Aslin, the county architect for Hertfordshire.
The system was used as a model for several other counties, most notably Nottinghamshire and Derbyshire. CLASP's popularity in these coal mining areas was in part because the system permitted fairly straightforward replacement of subsidence-damaged sections of building. The system was also later used for the construction of railway stations, offices, university buildings, and churches until the late 1970s.
Today, 3000 examples are still in use. While some of the buildings are listed, there are calls to replace others due to health concerns about asbestos used in their construction.