As a former FOSM, the author provides a personal view on CASD and its enduring legacy, as relevant to assuring the UK’s security as it has ever been. As a young Lieutenant in January 1969 I joined HMS Revenge (Starboard) crew as the submarine was building in Cammell Lairds in Birkenhead. This was the fourth boat after HMS Resolution, HMS Repulse (both built at Vickers Shipbuilding in Barrow) and HMS Renown and they were state-of-the-art at the time. The four boats were of British design with United States missile systems and missiles but UK warheads. Each submarine was armed with up to 16 Pola…