In 1966, a former pirate radio broadcaster, Major Paddy Roy Bates, occupied a disused military platform in the North Sea, and moved his family aboard. The next year he declared it to be the sovereign Principality of Sealand, appointing himself Prince Roy, and his wife, a former fashion model, as Princess Joan. Five decades on, the Bates family still occupy the platform, having survived the repeated attempts by the British government to evict them by legal means, and having fought off attempts by rival groups to seize the platform by force. It's a story of coups, counter-coups, guns, petrol bombs, and rival groups of foreign businessmen. Jolyon Jenkins interviews surviving witnesses to tell the story of this real life "Passport to Pimlico".