The 1586 beer barrels containing Mary Queen of Scots' secret letters

Mary Queen of Scots had a rather desperate habit of treating the local brewery like a high-security postal service. While under house arrest, she smuggled her treasonous correspondence inside the hollowed-out wooden bungs of beer barrels. It was a classic "message in a bottle" play, but with significantly more yeast and a lot more at stake.

The letters were rolled into tiny cylinders and shoved into the stoppers, allowing her to plot Elizabeth I’s demise while the guards just thought she was exceptionally thirsty.

The delicious irony? Her "trusted" brewer was actually on the payroll of Francis Walsingham, the world’s first true spymaster. Every secret she sent was essentially CC’ing her executioner.

Wait, how did they read the letters without Mary or the guards noticing?

Walsingham didn't just rip the bungs out; he had a professional "unboxing" team. A specialist named Arthur Gregory would delicately extract the cylinders without leaving a single scratch on the wood or the wax seals.

Then, a codebreaker named Thomas Phelippes—a man with a face like a shrivelled apple—would decrypt the messages and copy them. They’d then reseal the original letter and send it on its way, making sure Mary felt perfectly, and fatally, secure.

So how did this 'shrivelled apple' fellow actually crack a royal code?

Phelippes was essentially a human supercomputer with a very unfortunate complexion. Mary used a "nomenclator" cipher—a fancy way of saying she replaced common letters with zodiac signs, Greek characters, and even meaningless "null" symbols to throw people off the scent.

But Phelippes was a master of frequency analysis. He knew that in any language, certain letters are total attention seekers. By counting how often a specific squiggle appeared, he could deduce it was an 'e' or an 'a' and unravel the rest like a loose thread on a royal tapestry.

It was like solving a high-stakes crossword puzzle where the prize was a treason conviction. Once he cracked her logic, Mary’s private thoughts were about as secure as a diary left open on a pub table.

Hold on, did he actually tamper with the mail instead of just reading it?

Phelippes wasn't just a passive observer; he was a devious ghostwriter. After decoding a letter where Mary approved the plot, he added a forged postscript in her own secret code.

He 'asked' for the names of the six men supposed to do the stabbing. Mary, feeling secure in her beer-barrel bubble, helpfully provided the list.

It was the ultimate 'gotcha.' He essentially catfished a queen into writing her own death warrant, giving Walsingham the names and the excuse for the axe.

But how did she not spot a forgery in her own top-secret cipher?

Phelippes was a master of calligraphic mimicry, not just a mere clerk. He had spent years obsessively studying Mary’s handwriting and her specific way of drawing those zodiac-style symbols. To her, the forged postscript looked exactly like her own hand, right down to the slant of the ink.

Mary was blinded by confirmation bias and a crushing sense of isolation. When you’re trapped in a castle and think your beer-barrel system is foolproof, you aren't looking for a Trojan horse in the footnotes. She saw what she wanted to see: a golden ticket to the throne.