Britain receives the "Oslo Report"

On 4 November 1939, Captain Hector Boyes, the Naval Attaché at the British Embassy in Oslo, received an anonymous letter offering him a secret report on the latest German technical developments. To receive the report, all he had to do was arrange for the usual announcement of the BBC World Service’s German language broadcast to be changed to “Hullo, hier ist London”. This was done, and resulted in the delivery of a parcel a week later which contained a typewritten document and a type of vacuum tube, a sensor for a proximity fuze for shells or bombs.

It was only after the war that R.V. Jones revealed the importance of the material contained in the report:

[I]t told us that the Germans had two kinds of radar equipment, that large rockets were being developed, that there was an important experimental establishment at Peenemünde and that rocket-driven glider bombs were being tried there. There was also other information – so much of it in fact that many people argued that it must be a plant by the Germans, because no one man could possibly have known all of the developments that the report described. But as the War progressed and one development after another actually appeared, it was obvious that the report was largely correct; and in the few dull moments of the War I used to look up the Oslo report to see what should be coming along next.

The report had been written by Hans Ferdinand Mayer, the director of communications research at Siemens, who had access to a wide range of secret electronic development in Germany. He was simply motivated by his personal opposition to the Nazi regime. He was later to be imprisoned in concentration camps but the Nazi’s never learned of the existence of the report. Mayer survived the war and eventually his identity became known to R.V Jones through mutual scientific friends. However Mayer insisted that his identity as author of the report should not become public knowledge until after his death. Mayer died in 1980 and was identified in later editions of R.V. Jones classic war memoir Most Secret War also available from and

Frithjof A.S. Sterrenburg has written a comprehensive technical review of the report together with full German and English transcripts.