He was the author of the "Oslo Report", a major military intelligence leak which revealed German technological secrets to the British Government shortly after the start of World War II.
Both scientists concerned themselves with interference-free information transfer in long distance circuits, important in developing telecommunications.
Hans Ferdinand Mayer was the author of the Oslo Report, one of the most serious breaches of German security in World War II.
He signed it as "a German scientist, who is on your side", before sending it to the British Embassy in Oslo, Norway, in early November 1939.
In his position at Siemens he had access to a wide range of information regarding the development and application of electronics in current and future weapons systems and radar.
Jones, who was highly regarded by Winston Churchill and eventually rose to the position of Assistant Director of Intelligence (Science), found the Oslo Report extremely useful in anticipating and countering the deployment of new German radar systems, and the radio beam systems used to guide German bombers to their targets.
The existence of the Oslo Report became more widely known through a talk given by Jones in 1947, although he did not become aware of its author's identity until late 1953, finally confirming it by meeting Mayer in 1955.