We’re familiar with Bletchley Park, the English intelligence-gathering headquarters during the war. And we’ve probably all heard of Alan Turing, developer of electro-mechanical means to reverse engineer the German’s Enigma cipher machines.
Unless you’re a real crypto-nerd, you’ve probably never heard of Gordon Welchman, a peer of Turing’s at Bletchley who also organized the troops and introduced various new methods to analyze Nazi activity. In retrospect he’s the father of message traffic analysis which is akin to using metadata to track the activities of an individual or organization.
The BBC just did a documentary on him, and he even published a book which is what caused him much grief from the intelligence community. He died shortly afterwards.
Here are some more details, including a link to purchase his book. Which is out of print and stupid expensive.