Although I suspect that the A-Level maths students had a rather different presentation to ours, how excited was I, a Remove pupil, to learn about cryptography? It’s a big word. He clarified: code-breaking.

 

Donning my secret agent cap, I pondered the history of the Spartan Scytale. What messages did they wrap around the pole? Send more troops…Perhaps? What of Mary, Queen of Scots, and the Babington plot? Who knows, if her messages hadn’t been intercepted and decrypted, would the so-called traitors have survived? Might our religious beliefs, monarchy even, be different?

 

Now my journey with Grime takes me to the Enigma project. I envisage Bletchley Park, the code-breakers, and of course, Alan Turing: the man who cracked Enigma with his own machine, the Bombe. There, in front of us, sits a real Enigma machine.  “How much is it worth?” someone asks. He’s not allowed to tell us.

 

The questions come to me again. Is it possible that without the Bombe, we’d have lost World War Two? If the code-breaking had to be kept secret, who decided which information to act on and what to ignore?  More significantly, who would live and who would die?

 

Back in the decrypting present, Grime gives us some work to do. “It’s a game,’” he says.

“Glorified hangman,” he calls it. So we sit at our tables and decrypt the letters. Competition is fierce. He reminds us what to do: “most commonly used letters first, small words next, focus on gaps.”  We’ve got it. I think he’s pleased.