Superintendent Bunker, a communication specialist with 30 years service and now with Scotland Yard, has produced this definitive history of police communications. The book gives a detailed history of methods and equipment from the early watchman's rattle to the introduction of the 999 system in the nineteen thirties. The concluding chapters give an overview of the Metropolitan Police during World War II and the development of electronic data processing and transmission in post war years. The basic structure of the book is enlivened with byways of police communication including the capture of Crippen, the first clumsy radio tenders at Epsom in the nineteen twenties and the development of facsimile transmission from the air by the "Met" as early as 1932. The book is fully illustrated with over 100 photographs of early radio, telephone, police box, motor vehicle and aerial equipment used by London's police over the years, many illustrations being previously unpublished, from Scotland Yard's archives.