On Monday 30 October 1939, German engineer Hans Ferdinand Mayer arrived at Hotel Bristol. After checking in, he borrowed a typewriter from the hotel, and with it he typed one of the most spectacular leaked documents of World War II.
The seven type-written pages, which subsequently became known as the Oslo Report, described the Nazis’ weapons systems and latest technological development projects. Mayer sent it anonymously to the British Embassy in Oslo, and signed it “from a German scientist, who is on your side”.
The Oslo Report provided the British with a good foundation for developing counter-measures against the weapons systems described, and it was thus an important contribution to the British victory in the Battle of Britain.