The codebreaker Meredith Gardner recalled that Weisband had watched him extract a list of Western atomic scientists from a December 1944 NKVD message.
Later in the seventh series, Sam has a new love interest, Adam Wainwright, played by Max Brown, a former Bletchley Park codebreaker who proposes to her in that series' final episode.
John R.F. Jeffreys (1918–1941), British mathematician and World War II codebreaker
Rosalind Audrey Clare Hudson (née Latham 31 July 1926 – 7 July 2013) was a British codebreaker and architectural model maker.
To have it as a mnemonic "key" would have required a different method for the book's climax, either involving a "Bletchley Park" type codebreaker trick (some early "computer" perhaps) or by Vandam pressuring Wolff to reveal it (unlikely, given the obstinate history of the Nazi-Bedouin character).