The secret art of “letterlocking”

The secret art of “letterlocking”

Before the use of envelopes, people used ingenious methods to prevent prying eyes from reading their letters.

One such person was Mary Queen of Scots, who composed her last ever letter from prison. The night before she was to be executed, she penned a letter to her brother-in-law, then folded it up to secure the message from her captors - especially her cousin Queen Elizabeth I.

To do this, Mary cut a thin strip from the paper’s margin, then folded her letter into a small rectangle. After making a small hole in the rectangle with a knife, she then fed the strip through and looped and tightened it a few times, creating a “spiral lock”. Though no wax or glue was needed, any interceptors would have to break the strip to read the letter so her brother-in-law would know if another had read it before him.

Mary Queen of Scots wasn’t the only person to use this technique of “letterlocking”, which had become a common skill used throughout Europe from 1250-1815 AD. By folding and cutting letters in these kinds of patterns, people could hide their correspondence from unwanted readers.

“This isn’t something special that people do on special occasions. This is how you send a letter before the envelope is invented,” said Daniel Starza Smith, a lecturer in Early Modern English literature at King’s College London.

“So if it’s a business letter, if it’s a love letter, if it’s a spy letter, if it’s a diplomatic letter, they’re all using letterlocking. So it’s not something confined to experts, royalty or spymasters,” he said.

“Anyone who is capable of sending a letter is using letterlocking.”

A rediscovered skill

Our understanding of letterlocking has only developed in the last 20 years, after conservator Jana Dambrogio found evidence of the practice on letters from a cache of unrepaired 16th century Italian documents. Though the tears, creases, and folds could be mistaken for damage by an untrained eye, Dambrogio realised what they were and took her observations back to the United States.

“There are probably thousands of letters of the Vatican, but this handful that I modelled started to help us build the language of letterlocking,” she said.

After connecting with Starza Smith, Dambrogio and her colleagues have continued to search for more locked letters.

Over time, Starza Smith and Dambrogio developed a “periodic table” of letterlocking, which includes 18 different methods that vary in complexity.

The team have produced demonstrations of how many of these locks are made and have used X-ray techniques to virtually read letters without opening them.

Image: Unlocking History Research Group