In the Royal Navy vernacular, the term 'greenie' describes the officers and ratings responsible for the electrical engineering functions of the fleet. Electrical engineering has 'driven' the Royal Navy for far longer than one might imagine, from solving the problem of magnetic interference with the compass by the ironclad early in the 20th century onward. Author Commander Moore traces the development of technology from 1850 to today's integrated micro computers that control almost every aspect of navigation, intel, and strike capacity. At the same time, he describes how the Navy's structure and manpower changed to accommodate the new technologies, changes often accelerated in wartime, particularly in World War II. Without the full cooperation of naval establishments and organisations and various public and private museums and manufacturers, this work would have been impossible to produce. Written in an anecdotal, narrative style but with a complete mastery of the science itself, it will appeal not only to those interested in the history of the Royal Navy but also those many thousands, past and present, who can claim the honour of calling themselves one of the Greenies.