By Peter Day
12:01AM GMT 03 Jan 2002
ONE of the pioneers of British aviation was caught spying for the Japanese but was never prosecuted to protect MI5 operations, it was disclosed yesterday.
Lord Sempill was one of the founders of the Royal Flying Corps in the First World War and remained a pillar of the establishment until his death in 1965.
His father had been an aide to George V and he came from a long line of military men. But in the 1920s he sold aviation secrets to the Japanese naval attache, Captain Teijiro Toyoda.
A Foreign Office file released at the Public Record Office after 75 years shows how Sempill was confronted with his crime by diplomats who had blackballed him from a job as aviation adviser to the Greek navy.
At the time he was chairman of the Royal Aeronautical Society and went on to be its president. Despite his disgrace he rejoined the Royal Naval Air Service from 1939 to 1941.
Sir Vernon Kell, the head of the security service, persuaded Sir Arthur Bodkin, the Director of Public Prosecutions, not to prosecute Sempill because to do so would reveal that MI5 was intercepting diplomatic mail to and from the Japanese embassy.
They considered a separate charge after discovering that Sempill had talked his way into a hangar where a secret seaplane, codenamed Iris, was being built by the Blackburn Aeroplane Company.
Bodkin again advised against prosecution because Sempill was an occasional consultant to the company.
He added: “The company are by no means alive to the importance of acting upon that word ‘secret’. It would appear that any decent British person, who happened to be known to a member of the staff, could walk through the doors of the shed.”
Kell wrote to Victor Wellesley, under secretary at the Foreign Office: “The question of prosecuting Sempill has been considered on more than one occasion, but apart from the matter of the Iris, the evidence against him rests on photographic copies of letters written by him to the Japanese naval attache in London.
“It would, in my view, be in the highest degree undesirable to launch a prosecution based on such evidence as this as, even if the case were heard in camera, the proceedings must result in disclosing to Sempill, and consequently to the Japanese government our sources of information.
“When Sempill was seen by the deputy chief of the Air Staff and other officers, Sir Arthur Bodkin was present and warned him as to his conduct in the future, but gave him to understand that the matter of the Iris was at an end.
“Sempill was warned that, in view of his past indiscretions, in no circumstances would any official backing be given to him should he succeed in gaining employment under the Greek or any other foreign government.
“He now understands his position and I think realises that, so far from having any cause of complaint with regard to his treatment, he is fortunate in having escaped being prosecuted.”
Wellesley noted in pencil: “Kell wishes this letter to be destroyed after it has been read.” The Foreign Office had been embarrassed to discover that Sempill’s indiscretion had been known to MI5 for two years. It had been supporting his efforts in Greece that would have led to aircraft orders for the Blackburn company.
Sempill was outraged when he found out that there was a diplomatic whispering campaign against him and threatened to sue for defamation until the extent of the evidence was revealed to him.
He represented the government on aviation missions to America and Japan, where he was awarded the Order of the Rising Sun.
Baron Kato, the Japanese prime minister, wrote to Sempill thanking him for “the splendid results, almost epoch making, that have been brought about in the Imperial Japanese Navy”.