Mary Queen of Scots’ coded prison letters finally cracked

A team of codebreakers have cracked the long-lost secrets of Mary Queen of Scots’ letters that she wrote while imprisoned by her cousin Queen Elizabeth I more than 430 years ago. Experts believe this is the most significant discovery about Mary for more than a century.  

More than 50 coded letters were found, dating from 1578 to 1584, and expose fascinating insights about her time in prison. 

The letters were found in the French National Library, whose catalogue had listed them as Italian texts from the first half of the 16th Century. Experts believe this is why the letters took so long to be discovered. 

After starting to crack the code, the team “quickly realised” the letters were written in French and “had nothing to do” with Italy. 

George Lasry, a computer scientist and cryptographer; Norbert Biermann, a pianist and music Professor; and Satoshi Tomokiyo, a physicist and patents expert, discovered that it was Mary who wrote the letters after solving her highly sophisticated cipher system. 

Lead author Dr Lasry said, “upon deciphering the letters, I was very, very puzzled, and it kind of felt surreal. We have broken secret codes from kings and queens previously, and they’re very interesting, but with Mary Queen of Scots, it was remarkable as we had so many unpublished letters deciphered and because she is so famous. This is a truly exciting discovery.”

The cipher symbols and decryptions of one of the letters © Lasry, Biermann, Tomokiyo

Mary spent a total of 19 years in prison before she was beheaded on 8 February 1587. The team spotted several mentions of captivity and the name “Walsingham”, thought to refer to Sir Francis Walsingham, Queen Elizabeth’s spymaster. The letters reveal her distrust of Walsingham and Sir Robert Dudley, Earl of Leicester, who was a favourite of Elizabeth’s. 

The letters also mentioned her poor health, negotiations for her release, the conditions of her captivity and her distress over the abduction of her son (the future King James I), who was taken away from her at age one.  

Dr John Guy, a fellow in history at The University of Cambridge who wrote the 2004 biography of Mary Queen of Scots, said this discovery is a “literary and historical sensation” and marks the most significant new find on Mary for more than 100 years. 

He said, “these new documents, amounting to some 50,000 words, show Mary to have been a shrewd and attentive analyst of international affairs. They will occupy historians of Britain and Europe and students of the French language and early modern ciphering techniques for many years to come.” 

Dr Lasry and his team suggest that other letters from Mary may still be missing. 

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