Colonel Lord Sempill: The Peer Who Gave Japan the Secrets of Pearl Harbor He was a celebrated air pioneer, a Scottish peer, and a close friend of the Royal Family. He was also the man who taught Japan how to build an aircraft carrier—and then kept supplying secrets until the bombs fell on Pearl Harbor. When British Intelligence finally caught him red-handed in December 1941, just days after Japan invaded Malaya, they faced an impossible choice. Prosecute him for treason, or protect the reputation of the British establishment? They chose to protect the establishment. Who Was Lord Sempill? William Francis Forbes-Sempill, 19th Lord Sempill  (24 September 1893 – 30 December 1965), was a Scottish peer, record-breaking aviator, and aeronautical engineer  . Before the war, his credentials were impeccable: Credential Details Education Eton College  WWI Service Royal Flying Corps → Royal Naval Air Service → Royal Air Force  Awards Air Force Cross (AFC), Fellow of the R...