"Oh thank you so much," said Noma. "Look. Here's what I really wanted to show you. I took photos of the note before it got ripped."

"I don't know what it means," said Ellie, "but I think it's important."

"Can I have that interview now?" asked Noma. "What do you know so far? How many of the drums have you found and what on Earth is this all about?"

"Perhaps we should fill you in," said Ellie.

"Alan Turing was working on psychohistory, but kept the results of his research hidden. He left clues about where to find the information to his former student Barquith. These four clues are all hidden in specially modified drums of the Bombe. We've got three of the clues and we know that the final drum is in the Rochdale canal."

"What are we waiting for?" said Noma. "Let's go and get it. I'll get my diving gear?"

"You've got diving gear?" boggled Mike.

"You never know where an investigation is going to take you," said Noma.

"Wait," said Ellie. "Before we go rushing off, don't forget that somebody else is after the drums. Barquith was attacked in his office and the box was stolen and the drum buried in the Peak District was dug up before we got there. Thanks to Mike anybody who follows his chirps will know where we've been and where we are...." she broke off. Mike was typing into his phone. "Mike!" she yelled, "will you stop telling everybody where we are all the time!"

"Let's go and get Noma's diving gear, but we must be careful."

Noma's head broke through the surface of the canal. She took the mouthpiece out. "It's very murky down there," she said, "but I think that I saw something of about the right size." She flipped over and disappeared again. After what seemed like the age of the universe, but was probably only a minute or two, a hand emerged from the canal and threw an object to Mike and Ellie on the bank.

"Just call me the lady of the canal," grinned Noma as she clambered out. "Is that it?"

"Yes," said Ellie. "We've got the last clue, but we'll all need to put our heads together to solve it."

Below is the scrap of paper. It contains a secret message. Once you have found the message, you should enter the entire plaintext in the box below.

Alan Turing Cryptography Competition 2020 is organised by the The Department of Mathematics at The University of Manchester.
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