In 1968, after the convictions of Douglas Britten, G3KFL, newspapers reported the potential threat to national security posted by the amateur radio callbook. Here is the clipping from the Nashua Telegraph published on November 13, 1968:
The story was sourced from The Tome of London. Concern was expressed that the Amateur Callbook listed hundreds of service personnel with access to secret information. This was the time of the cold war and the Soviets could use this information to contact potential sources of classified information.
The story was triggered by the conviction of Douglas Britten G3KFL, described as a “Royal Air Force wireless operator”, under the Official Secrets Act. Britten was reportedly “approached through amateur radio“. The newspaper says “A man who said he was a Russian ham operator went up to him in the Science Museum in Kensington in 1962 and addressed him by his call sign G3KFL“.
This source lists Chief Technician Douglas Britten G3KFL (born October 31 , 1931), as an RAF Signals Intelligence Specialist serving at 399 Signals Unit, RAF Digby in Lincolnshire.
A fascinating story, since at the time of his conviction, I was myself working in US Army Security Agency intelligence.