A pillar of the British establishment was passing secret information about aviation design to Japan during the 1920s, according to secret government files declassified Thursday.
The British Foreign Office files from 1926 show that Lord Sempill, reputedly one of the founders of the Royal Flying Corps in World War I, passed details of British "aeronautical construction" to the Japanese naval attache in London, Capt. Teijiro Toyoda.
The records, which have remained classified for the last 75 years, indicate that the espionage took place roughly between 1922 and early 1926.
He escaped prosecution only because MI5, the British counter-intelligence agency, wanted to protect its operation monitoring diplomatic mail to and from the Japanese Embassy in London, according to the records.