The wartime girls.

Vrouwen in de Tweede Wereldoorlog

Revealed: identity of Fifi the stunning wartime spy

National Archives has revealed the identity of the female spy, who was called “Fifi”.
Fifi was ordered to test trainee spies, but only a few knew of her existence. After the war, the existence of a Second World War secret agent codenamed ‘Fifi’ was to be thought as fiction.
But now, almost 70 years later, Fifi’s existence has been confirmed by MI5. Her real name was Marie Christine Chilver, hired at 22 by the wartime Special Operations Executive.
Fifi past away in 2007.

Full article in The Telegraph:

Marie Christine Chilver-Fifi