On the afternoon of December 7, 1942, a stunning 22-year-old blonde scanned Liverpool’s State Café and spotted her prey. The target matched the brief description given to her—26 years old, black moustache, sallow complexion and large brown eyes. The small moles on the left cheek and the right side of the chin of José Tinchant left no doubt that this was her mark.

She approached the British spy-in-training and asked, “Are you by any chance Mr. Tas?” The surprised Tinchant, who was awaiting a tall man with blue eyes, was briefly speechless before muttering in the affirmative. “Oh! I have been asked to help you,” the elegantly dressed woman said as she took a seat at his table and introduced herself as French freelance journalist Christine Collard. She explained that she was writing about war transport and had been instructed to meet him and be as useful as possible. The pair spent the day together—sipping coffee in cafes, watching a movie at a local cinema and enjoying a late dinner. Under orders not to disclose information to anyone without a password, the fledgling spy let his guard down around the attractive young woman and revealed nearly every detail about his family, his training exercise and his impending sabotage mission to his native Belgium.

“By the evening I had learnt practically all there was to know about him,” Collard reported to her superiors, which was bad news for Tinchant because the young woman was not a scribe at all but a secret agent with the codename “Fifi” dispatched by Britain’s Special Operations Executive (SOE), the covert World War II espionage agency created by Winston Churchill, to test whether spies-in-training would “spill the beans” and compromise their secret missions. Once Agent Fifi delivered her report, Tinchant’s espionage career was over before it even began.

For decades rumors had circulated about a seductive female agent provocateur employed by the British during World War II, and a once-secret file with more than 200 pages of handwritten correspondence and intelligence reports released online by Britain’s National Archives for the first time yesterday not only confirmed her existence but revealed her true identity—Marie Christine Chilver. “‘Fifi’ was something of a legend of the Special Operations Executive,” said National Archives researcher Jonathan Cole. “Until now, her existence and the deployment of her services had been dismissed but with the release of this file, her identity, impressive skills and the important role she played in Second World War secret operations is now finally revealed.”

Chilver was born in London in 1920 to an English journalist father and a Latvian mother. She was raised in Riga, Latvia, and attended a German school before traveling to Paris in 1940 to study French at the Sorbonne. After the Germans seized Paris, she was sent to an internment camp in Besancon before escaping with British prisoners of war. She reached England in October 1941 along with a wounded British flight lieutenant who called her “one of the most expert liars in the world” and suspected she was a German spy because she looked too hale and hearty to have been a prisoner. British intelligence officials not only cleared her of suspicion after close questioning but thought her “quite unusual gifts of intelligence, courage and assessment of character” and her fluency in German could be potential assets. With no money and no job, Chilver agreed in the fall of 1942 to encounter trainees from the SOE’s “finishing school” on their 96-hour undercover exercises around Britain and test whether they could keep their secrets.

Chilver’s true identity was known to only a handful of intelligence officials, and her meticulous and nuanced reports could make or break the futures of trainees such as Tinchant. Agent Fifi tested female trainees as well as men, and nothing in the files indicates that her encounters with the targets ever went beyond conversation, although in one report she mentions that a trainee invited her back to his hotel, only to ask her to hem his silk scarves.

Agent Fifi’s superiors found her “very intelligent, quick and well-informed” with a “considerable imagination.” However, they repeatedly refused her requests for raises, and her dream of becoming an agent in France remained unfulfilled. After the war ended, she left the intelligence service and lived in England. Using compensation from the Soviet Union for property seized from her family in Latvia, she set up an animal shelter in Riga in 2001 before her death in 2007.

The records released by the National Archives not only revealed the unknown Agent Fifi but included scores of articles, letters and manifestoes written by perhaps Britain’s most notorious World War II traitor—William Joyce. Born in Brooklyn and raised in Ireland, Joyce became a fascist leader in the 1920s after moving to England. Just days before Nazi tanks roared into Poland in 1939, Joyce fled to Germany after learning of British plans for his internment. The Nazis employed him to write scripts and deliver English-language propaganda radio broadcasts with inflated casualty reports and misinformation designed to demoralize the British people and English-speaking troops. Joyce’s voice first crackled through the airwaves on September 18, 1939, and soon millions of British radios tuned in to his broadcasts that opened with the announcement “Germany calling! Germany calling!” The smug attitude and clipped, upper-crust English accent feigned by Joyce earned him the derisive nickname “Lord Haw-Haw” from the British public, but his broadcasts were no laughing matter to the British military. “Though the British public’s first reaction was one of amusement,” said a December 1939 War Office memorandum, Joyce’s broadcasts were “becoming a definite factor affecting public morale in this country.”

Joyce broadcasted his missives until the end of the war. His distinctive voice ultimately proved his downfall when British soldiers recognized it and arrested him. Although an American citizen and a naturalized German, Joyce was tried, convicted and executed for high treason based on his British passport.

Also among the 3,300 Security Service records released by the National Archives are files on Cecil Day Lewis, the father of actor Daniel Day Lewis and United Kingdom poet laureate who joined the Communist Party in the 1930s; Ralph Baden Davenport Powell, a Nazi propaganda broadcaster and relative of Boy Scouts founder Lord Baden-Powell; British Union of Fascists founder Sir Oswald Mosley and Nazi leader Rudolph Hess.