Nathalie Sergueiew

Nathalie "Lily" Sergueiew (1912–1950) was a female double agent who worked for MI5 during World War II under the codename "Treasure". She played a significant role in deceiving the Germans about the location of the D-Day landings.

Biography
Sergueiew was born in Saint Petersburg, Russia (niece of General Yevgeny Miller ), but her family fled to France following the Russian Revolution in 1917. She was educated in Paris, and trained as a journalist, being fluent in English, French and German. During the mid-1930s she travelled extensively throughout Germany, and once interviewed Hermann Göring.

An attempt was made to recruit her by the German intelligence service in 1937, but she refused. However, after the fall of France she agreed to work for the Abwehr. Her case officer, Major Emil Kliemann, trained her in intelligence gathering and communications techniques, and in 1943 she travelled to Spain, taking her beloved dog Frisson with her. Sergueiew promptly contacted the MI5 representative in Madrid and reported herself as a German spy and offered to work for British Intelligence. She was accepted, and travelled to England. Unfortunately British quarantine regulations meant that Frisson was left behind at Gibraltar.

Sergueiew was given the code-name "Treasure" and handled by MI5 officer Mary Sherer. "Treasure" turned out to be an effective agent, but was also described as "exceptionally temperamental and troublesome". She revealed her role as a double agent to her American boyfriend, and threatened to quit unless MI5 arranged for her dog to be brought from Spain. Matters came to a head in May 1944 when "Treasure" learned that Frisson had died. She informed MI5 that she had a pre-arranged secret signal, which would indicate to Kliemann that she was under British control, and threatened to use it in revenge for the death of her dog. After a tumultuous meeting with Colonel T.A. Robertson, head of the section responsible for control of the Double Cross agents, she eventually revealed the secret code. "Treasure" continued to work for MI5, sending the Germans false information until a week after D-Day when she was informed that her services were no longer required. However, MI5 continued transmitting messages from her for another five months.

Sergueiew returned to France in late 1944, where she served in the French Women's Army Service. After the war she wrote a revealing memoir describing her former employers as "gangsters". Sergueiew later emigrated to the United States where she died in 1950. Her memoirs, entitled Secret Service Rendered, were eventually published in 1968.