Scores of secret letters from Mary, Queen of Scots, discovered by codebreakers

The surprise discovery of nearly 60 coded letters written by Mary, Queen of Scots, while she was held prisoner in England has been hailed as a “literary and historic sensation”.

The letters were found in the French national library (Bibliothèque nationale de France), where they were catalogued simply as enciphered documents and stored with early 16th-century papers dealing with Italian affairs.

Their royal provenance was not recognised until after George Lasry, a computer scientist and cryptographer, Norbert Biermann, a pianist and music professor, and Satoshi Tomokiyo, a physicist and patents expert, stumbled upon them while searching the archive for historic documents in undeciphered code.

Most of the 57 secret letters were sent from the deposed Catholic queen to Michel de Castelnau, the French ambassador to England. They date from 1578 to 1584 — only a few years before Mary’s beheading on February 8, 1587 — and discuss English, Scottish and European politics and the English succession.

In the newly deciphered missives, Mary expressed her goodwill towards her Protestant cousin and captor Elizabeth I of England, but sought French protection for Scotland’s independence. She suggested that, if France should fail to support her and her son James’s interests, Scotland should ally with Spain rather than succumb to English domination. She also told Castelnau that she wished to bring England back to Catholicism, but not by force.

The researchers identified the letters’ authorship after using a codebreaking algorithm and manual techniques to unravel the queen’s cipher, which used 219 distinct symbols. They said they quickly realised they were written in French and “had nothing to do with Italy”. Several mentions of captivity and the name “Walsingham” first aroused their suspicions that they might be from the famous Scottish monarch.

They subsequently identified copies of seven of the deciphered letters in plain, uncoded text, held in British archives. These copies, which were leaked by a mole in Castelnau’s embassy to Queen Elizabeth I’s spymaster Sir Francis Walsingham, helped to corroborate the letters’ origin.

Commenting on the study, historian John Guy — who wrote the 2004 biography of Mary which led to the 2018 film starring Saoirse Ronan and Margot Robbie — said the letters were the most significant find relating to the queen in a century.

He said: “This discovery is a literary and historical sensation. Fabulous! This is the most important new find on Mary, Queen of Scots, for 100 years. I’d always wondered if de Castelnau’s originals could turn up one day, buried in the Bibliothèque nationale de France or perhaps somewhere else, unidentified because of the ciphering. And now they have.”

Mary, the daughter of James V of Scotland and Mary of Guise, was queen of Scotland from 1542 until her forced abdication in 1567, and queen consort of France in 1559-60. As a descendant of the Tudor monarch Henry VII, she was considered by some Catholics to be the rightful ruler of England and was held captive for 18 years after seeking the protection of her cousin Elizabeth. Mary was eventually executed, aged 44, after sending a letter, in cipher, backing a plot to assassinate the English queen.

Recurring themes in the newly deciphered letters include Mary’s complaints about her health and conditions in English captivity, and negotiations for her release, which she believed were not conducted in good faith. The researchers said Mary’s distrust of Walsingham was also apparent, as was her animosity towards the English queen’s sometime favourite, Robert Dudley, Earl of Leicester.

In a letter of May 2, 1578, Mary — imprisoned in Sheffield Castle, Yorkshire — told Castelnau she proposed to reassure Walsingham of her good intentions and her agreement to remain in captivity as long as her rights, and those of her son James, to the English throne, were preserved. She expressed her intention to return England to the Catholic faith by peaceful means.

Another topic of discussion in the letters was the proposed marriage between Elizabeth and the Duke of Anjou. Mary expressed support for the Anglo-French match, and said she was happy about the possibility, suggested by Castelnau, that Elizabeth might convert to Catholicism if it went ahead. Nevertheless, she told the ambassador that the English side was not sincere and only intended to weaken France and counter Spain by encouraging the duke to attack Spain in the Low Countries. After the duke’s campaign in Flanders ended in disaster, as she had warned, Mary offered to help in reconciling the duke with the king of Spain.

In a letter of June 12, 1578, Mary thanked Castelnau for mitigating Elizabeth’s outbursts of anger against her, which, she said, occurred despite Mary’s respect for her cousin. On November 6, 1581, Mary told Castelnau that, when the Earl of Leicester was closer to Elizabeth, he had advised Mary to write openly and freely to her and said that, while the queen might sometimes get offended and angry, she eventually cooled down. Mary said she had tried to demonstrate her goodwill towards the English queen.

Four years later, in the summer of 1582, she told Castelnau that, should an English-linked rebellion take place in Scotland, she wanted France to intervene in the name of the old alliance between the two countries. She said she was loyal to France and able to ensure the loyalty of her son, who was reigning in Scotland as James VI. She insisted that France should prevent Scotland from falling under England’s control.

“This is a truly exciting discovery. The letters constitute a voluminous body of new primary material on Mary Stuart”

George Lasry

The following October, Mary told Castelnau that some of her most loyal Scottish followers had cooled towards France, because their devotion had not been rewarded and nothing came from the nice words and promises of the previous French ambassador, de la Mothe-Fénelon. She said those noblemen, and her son James, might fall for overtures from Spain, as being deprived of the support of France, they might look for it elsewhere. Mary said that she would prefer this to seeing them succumb to their enemies.

Mary’s gratitude towards Castelnau is evident in the letters. In April 1583, she wrote: “I cannot thank you enough for the care, vigilance and entirely good affection with which I see that you embrace everything that concerns me and I beg you to continue to do so more strongly than ever, especially for my said release to which I see the queen of England quite inclined.” Nevertheless, at other times, she expressed fears for her life.

Lasry, the study’s lead author, said: “This is a truly exciting discovery. Together, the letters constitute a voluminous body of new primary material on Mary Stuart — about 50,000 words in total, shedding new light on some of her years of captivity in England.

“Mary, Queen of Scots, has left an extensive corpus of letters held in various archives. There was prior evidence, however, that other letters from Mary Stuart were missing from those collections, such as those referenced in other sources but not found elsewhere. The letters we have deciphered are most likely part of this lost secret correspondence.”

The existence of a confidential communication channel between Mary and Castelnau was known to historians and even to the Elizabethan state. However, Lasry and his colleagues have identified a trove of material previously unseen by scholars, as well as evidence that this channel was already in place as early as May 1578 and active until at least mid-1584.

Lasry added: “In our paper, we only provide an initial interpretation and summaries of the letters. A deeper analysis by historians could result in a better understanding of Mary’s years in captivity. It would also be great, potentially, to work with historians to produce an edited book of her letters deciphered, annotated and translated.”

The top image shows Saoirse Ronan starring as Mary, Queen of Scots, in the 2018 film based on John Guy’s biography. Photo: Alamy