This volume contains a history of the origins and organizations of these laboratories and an account of the philosophies on which they were based. The authors then highlight research in each of the decades between 1920-1980, and the contributions each laboratory made. Specialist chapters focus on such areas as lamps and lighting, valves, communications and semiconductors. Sections cover the work done on solid state physics in the 1950s and 1960s, the research conducted on optical fibres and communications since the 1970s, and the individual patents and publications of the laboratories.