Spy Ring Letterbox Hybrid

Jan 5, 1943
HF monitoring stations on the coast of England have intercepted coded communications between Germany and a clandestine station in Great Britain. While the German transmissions have been lengthy and easily copied, the transmissions from within GB have been short and weak, making triangulation difficult. One hideout has been found but only shortly after being vacated in Lynton, England. Documents found behind a loose brick in the fireplace we believe will be of assistance breaking encrypted intercepts. We are unable to understand the significance of the contents. We believe it is part of key required to decrypt messages to this station. It appears this agent has access to secrets at the highest levels. See attached. We have checked all documents for secret writing of anthracene and microdots but results were negative.

From this port town a small boat was reported stolen. It is suspected he is heading north where it is believed his spy ring is headquartered. We need your help to find his hidden cache.

Nigel de Grey, Deputy Director
Room 40
Department of Communications
Bletchley, Buckinghamshire

Historical notes:

1. Later in the war a British citizen that was spying for Germany, was recruited as a double agent to work for England, sending altered information to Berlin; code name "Snow."
2. Nigel de Grey had distinguished himself in British service during WWI with his cryptanalytic efforts in 1917 by solving the Zimmerman telegram.