"One of our nuclear warheads is missing" - The 1971 THROSK Incident

On a dark February day in early 1971 off the coast of Plymouth, there was rising concern about the fact that the unthinkable had happened. The small elderly Naval Armaments Vessel (NAV) THROSK, on passage to the Royal Navy Armaments Depot Coulport, in Scotland, and carrying Polaris nuclear warhead sub-assemblies, had vanished. Warships put to sea, and helicopters from RNAS Culdrose were launched in a desperate search operation to find her. Despite this, no sign could be found. At 0824 that morning, Flag Officer Plymouth sent a SECRET signal initiating the procedures for a possible ‘Nuclear Weapon Accident’ and the Royal Navy prepared for the previously unthinkable reality that one its strategic nuclear warheads was missing… This sounds the stuff of good Cold War fiction, or a scenario from a disaster planning exercise. In fact it is completely true and represents an all but forgotten story of the early days of the Polaris force and the challenges faced by the Royal Navy as it set up ...