It was vital to MI5
to make the communications sent by double agents to Germany as convincing
as possible. At first Treasure sent messages to Kliemann in secret
ink or encoded letters, but later she used a radio transmitter set.
She passed to him false information concocted by MI5 as part of
an elaborate and successful deception plan to keep D-Day
secret. Treasure led Kliemann to believe that there were very few
troops in South West England and that she had a boyfriend in the
14th Army (a non-existent unit invented by the Allies). This information
fitted in with messages from other double agents and supported the
Germans’ false belief that the Allies would land at Calais
rather than in Normandy. In this letter the deputy head of the Government
Code and Cypher
School thanks Sergueiew and her colleagues for helping to break
codes and deceive the enemy.