Elizabeth's Spy Network

Page 3 of 6

• 1. The Queen in danger
• 2. Walsingham and his spies
• 3. Coded letters
• 4. The Babington plot
• 5. Mary's downfall
• 6. Find out more
• Print entire article

Coded letters

Intelligence work also involved learning how to break the different codes used by plotters in their correspondence. Often, letters of the alphabet were shuffled in a certain sequence and, once the key was worked out, the message could be read and understood. Alternatively individual letters could be substituted with numbers, symbols or signs of the zodiac. But spies had to learn not only how to decipher code but also how to write it themselves. This was frustrating and time-consuming work, paid off only by the satisfaction of finally cracking a difficult code.

'...spies had to learn not only how to decipher code but also how to write it themselves.'

Some codes could only be understood by placing a sheet of paper punched with holes over the top so that just the relevant letters making up the message could be read. Success therefore depended on calculating the exact sequence of thousands of holes. Also popular was the practice of conveying information in invisible ink. Written in milk or lemon juice, the secret message could be read as the page was warmed over a candle and the letters appeared. Innocent text in normal ink was often written alongside the hidden message in order to throw a spy off the scent.

Walsingham knew that this work was critical to his success, and established a spy school to provide formal training for recruits. The security of the country was at stake, after all. Mistakes were unthinkable.

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Published: 2001-05-01