LONDON: The secret lives of some of the world’s most revered spies — including the most notorious exotic dancer Mata Hari – Dutch spy who was executed for spying for the Germans , has now been revealed.

Britain on Thursday declassified the top secret files of spies during World War I held in the archives of the country’s intelligence agency MI5.

More than 150 files are being made available in the digitized release as part of National Archives’ campaign to mark the centenary of WW1 in 2014.

The documents include information on Arthur Ransome, author of the children’s novel Swallows and Amazons and Sidney Reilly, a Russian-born adventurer whose exploits with the British Secret Service were the inspiration for James Bond.

The files contain a wealth of material about organisations such as the Bolshevik Party, British Communist Party and The Boy Scout Association and individuals like American poet Ezra Pound, political figures, from known fascists to communists and Russian leaders such as Leon Trotsky and Vladimir Lenin, who were involved in espionage or under surveillance during the period of WW1.

The files include rare pictures, letters, post cards and interrogation reports.

Dr Stephen Twigge, records specialist at the National Archives said “The files in The National Archives’ collection reveal the importance of the security service in safeguarding the nation during the WW1. Now that we have made the files available online, people across the globe can discover the secret history behind the war for themselves”.

One of the most interesting releases is information on Mata Hari and the secrets in which she hey traded.

The dossier talks about how Dutch-born Hari tried for causing the deaths of 50,000 soldiers by spying for German intelligence was arrested in February 1917 in Paris before being executed in France aged 41.

Her file includes photos from publications and newspapers about her arrest, conviction and execution including letters and an interrogation report.

Among the documents is an inventory of Mata Hari’s possessions when she was detained by Scotland Yard — a hat box with six hats, a feather boa, one veil, two fur necklets and an imitation peach.

A MI5 memo, referring to the spy by her real name of Margreet Zelle MacLeod talks about how the agency was alerted by their contact in Paris about the woman.

It says “He informs us that he has suspected her for some time and pretended to employ her in order, if possible, to obtain definite proof.”

MI5’s informant in The Hague, codenamed “T” reported “Mata Hari is a demi-mondaine who is in relation with highly placed people and during her sojourn in France she made the acquaintance of many French and Belgian officers. She is suspected of having been to France on an important mission for the Germans”.

Mata Hari was in November 1916 questioned by MI5 where she claimed that a French consul in Spain had subsequently asked her to go to Austria to spy on that country’s forces.

A French intelligence report dating back to May 22, 1917, later shared with a MI5 officer in Paris noted “Mata Hari confessed that she has been engaged by Consul Cremer of Amsterdam for the German Secret Service. She was paid 20,000 francs in advance”. She was shot by a French firing squad in 1917.

The documents also contain information about Edith Cavell — a British nurse, arrested, tried by German military court and executed. The documents contain photos of nurse Cavell’s grave at the site of the execution in Belgium. The photos were sent by the French authorities to MI5 to pass on to her mother. There is a letter in response from Cavell’s mother, thanking them for the photos.

The dossiers made public also talks about George Bacon — a German spy in the WW1. An American journalist recruited in New York, he was sentenced to death in 1917, later commuted to life imprisonment. Bacon was found in possession of materials for writing invisible messages; these were discovered after chemical tests were carried out on socks in his possession. The files include a letter to the home secretary from Bacon begging for a pardon from the British government. In it he states “The adventure for which I was punished was a foolish and theatrical one not done through hatred of Great Britain or her allies, but simply for excitement.”

He goes on to talk of his English ancestry and that Sir Frances Bacon is a relative of his. He also states that “there is no financial reason for asking for a pardon but the blood in my veins is English.”