Mary Queen of Scots: Decoded letters from captivity reveal a monarch 'unfiltered'

Decoded letters written in secret cyphers by Mary Queen of Scots during her imprisonment have revealed a woman of high intelligence and political nous who believed she was “going to win”.

More than 50 letters, which were found in the Bibliothèque Nationale de France and whose author was previously unknown, have been decoded by a team of computer scientists with historians now deployed to offer context to the correspondence which was written between 1578 and 1584 during her 19-year captivity.

The letters were written at various locations throughout the north of England as she was moved around properties linked to supporters of her nemesis-in-chief Elizabeth 1, who bitterly fought Mary for the right to rule England and who ultimately ordered her execution in 1587 after Mary was found guilty of plotting to kill her cousin.

Professor Estelle Paranque of Northeastern University in London has been working with the decoded Mary Queen of Scots letters. | contributed

Professor Estelle Paranque, a bilingual expert in early modern and public history, was brought in by the team of codebreakers to offer French historical perspective to the letters along with historian and author Dr Alex Courtney, an expert in the Stuart dynasty.

Prof Paranque said the letters changed the narrative on Mary being a “victim or martyr”.

She said: “I’m not a Mary fan, and for a long time I thought she was stupid, [but] she is not. She absolutely is intelligent. She is massively politically astute. I thought she made mistakes — she didn’t make mistakes; she made decisions. I thought that maybe she was a pawn in her family. She is not. She’s actually the one giving orders.

“What is incredible about these letters is that they reveal Mary as someone who speaks her truth.

READ MORE: ‘Lost letters’ of Mary Queen of Scots deciphered by international team of codebreakers

“She gives her orders and she shows incredible understanding of English and French politics. She shows incredible mastery of diplomatic language.

“We have an idea of her as a victim and these letters, if you take them from the beginning and you pretend you don’t know the outcome, that she is going to lose, when you read these letters you don’t get a sense that she is going to lose.

“For me it has been mindblowing just to have her voice unfiltered. It is Mary unfiltered and for me it is a new Mary.”

Mary wrote the letters while in the custody of the Earl of Shrewsbury, who was selected as her keeper after she fled to England following the disastrous Battle of Langside in 1568 which signalled the end of her reign in Scotland.

Letters were sent from Tutbury Castle, Sheffield Castle, Sheffield Manor, Winfield Manor and Chatsworth House with the majority of them addressed mostly to Michel de Castelnau, seigneur de La Mauvissière, the French ambassador in London between 1575 and 1585.

Elizabeth I is mentioned in the letters as is Robert Dudley, Earl of Leicester; Henry Hasting, Earl of Huntington and William Cecil, the chief advisor to Elizabeth I.

A sheet of cyphers used by Mary Queen of Scots in her correspondence written during captivity. PIC: Lasry, Biermann, Tomokiyo. | Lasry, Biermann, Tomokiyo.

Mary took “great interest” in the marriage negotiations between the Duke of Anjou, the son of King Henry II of France, and Elizabeth I , which began in 1579 with a promise of the nuptials protecting England against deteriorating relations with Spain.

Despite a 22-year age gap, the Duke was the last serious contender for Elizabeth’s hand in marriage and to provide an heir. The marriage contract was disbanded two years later.

Prof Paranque said: “Mary is very aware of this, she has very strong opinions about this , she is discussing it with her cousin, with her secretaries, she is discussing it in her letters to the French ambassador to the English court.”

Reference to the Throckmorton Plot, a conspiracy in 1583 to assassinate Elizabeth I and place Mary on the English throne, also emerges in the letters.

Prof Paranque said: “It is unsane. It is all unfiltered, you can see how smart she is, she knows exactly what they’re doing. And it shows us how well her network was working.

She added; “What I love about these letters as a historian is that, if you don’t know the ending, it is a real thriller.

“You feel her hopes , the prayers, the fears and what she was up against.

“And what is interesting too is how much Mary understood the political game. She knew exactly who her enemies were, and I didn’t realise how much she understood that.”

Prof Paranque described the correspondence as the “missing puzzle” of “so many other letters”.

She added: “I think they confirm what people had thought.

“These letters are not just historical context or missing puzzlues, they are about Mary’s personality - her real personality and not the myth of the victim or the martyr.”

The letters were decoded by George Lasry, a computer scientist and cryptographer; Norbert Biermann, a pianist and music professor and Satoshi Tomokiyo, a physicist and patents expert.

The letters were listed in the Paris archive catalogue as being from the first half of the 16th Century and relating to Italian matters. The team quickly realised the documents were actually written in French. Their detective work revealed verbs and adverbs often in the feminine form with suspicions arising about the author given several mentions of captivity and Walsingham.

More than 150,000 symbols were decoded by the team after they worked with the letters with around 50,000 words now recorded.

Prof Paranque said: “ The computer scientists have done tremendous work on these letters, they are the ones who discovered them and who then brought in historians to add context. I am so honoured to be part of that team.”

-The Secret Correspondence of Mary Queen of Scots is due to be published by Routledge in 2026.