‘Between Silk and Cyanide’ is the memoir of Leo Marks, one of S.O.E.’s (Special Operations Executive) main cryptography-wranglers during World War Two. It’s funny, fascinating and poignant by turns; the ins-and-outs of how codes work are rendered just as gripping as accounts of internal politics, the activities of agents in the field (such as the operation to destroy the Vermork heavy water plant in Norway), and Marks’ attempts to persuade his superiors to do things like accept the use of something more secure than poem codes, or acknowledge that S.O.E.’s network in Holland had been fatally compromised.
The title comes from Marks’ summing up of a significant dilemma affecting the safety of agents in the field: encipher messages using worked-out keys (WOKs) and letter one-time pads (LOPs) which were printed on silk and thus could be easily destroyed after use (so the codes/keys couldn’t be tortured out of them), or continue to use the frankly feeble poem-codes and be forced to swallow a cyanide pill in order to avoid capture and torture.
After finishing the book, I had to lay it aside for a moment and give a mental salute to a great many of S.O.E.’s people, including but by no means limited to: Leo Marks himself, Violette Szabo, Noor Inayat Khan, F.F.E. ‘Tommy’ Yeo-Thomas, the coders of Grendon, all the agents who were dropped to their doom in Holland…
I would definitely recommend this book to anyone who is interested in learning about SOE and/or the lesser-known (non-Bletchley) parts of the ‘code war’.