I’ve been having World War II at my house for the last several months: the war as seen through the eyes of the French Resistance. I’ve read so many biographies of spies that I am beginning to get them all mixed up. One book I am not likely to ever forget, however, is called Between Silk and Cyanide, written by the English cryptographer Leo Marks. Twenty-two years old when he joined the “war effort,” He had me with his first page:

“In January, 1942 I was escorted to the war by my parents in case I couldn’t find it or met with an accident on the way. . .Mother’s farewell to her only child was the public’s first glimpse of open-heart surgery.”

Leo Marks’ father owned Marks and Co., the bookshop made famous by Helene Hanff in 84, Charing Cross Road. That story took place later, in 1949, but Marks and Co was already a well-known antiquarian book shop in London. Sigmund Freud, “the great decoder of unconscious signals,” patronized it in the last year of his life after his escape from Nazi occupied Vienna. He sat in a comfortable chair and the staff brought him books for his research for Moses and Monotheism.

The book shop was where Leo Marks was first introduced to coding. Precocious as a child, he figured out the (secret) pricing code booksellers used. When the war began he was accepted at the school for cryptographers:

“I’d written to the War Office, the Foreign Office, and the Admiralty, enclosing specimens of my home-made codes with a curriculum vitae based loosely on fact, but no more loosely than their formal replies stating that my letters were receiving attention.”

In fact he was the enfant terrible of S.O.E.—Special Operations Executive, the secret organization created by Churchill to employ sabotage and subversion in Nazi-controlled Europe. He was a cryptographer whom Bletchley Park had overlooked because his first teachers had no imagination and didn’t recognize genius when they encountered it. Bletchley Park was itching to get him but S.O.E. wanted to keep him and Leo preferred its rogue atmosphere.

His interview with S.O.E took place in “a large private house which tried to ramble but hadn’t the vitality.” He was given a message in code and told to break it. He worked at it all day while his interviewers shook their heads. The FANYs could have broken the code in 20 minutes. When he finally handed in his de-coded message, he was told to leave the code with it.

“‘What code, sir?’

‘The code you broke it with.’

‘You didn’t give me one, sir.’

‘What the hell are you talking about? How did you decode that message if I didn’t give you one?’

‘You told me to break it, sir.’

‘You mean you broke it without a code?’

I had always understood that was what breaking a code meant, but this was no time for semantics.”

He was in.

As I read about all the inter-departmental squabbling in secret intelligence I wondered how short the war might have been had they all actually got along and communicated with each other. MI-6 thought S.O.E. was a bunch of amateurs who disrupted their quiet intelligence gathering operations so they withheld transport and information from them. De Gaulle, in London through much of the war, wouldn’t share information with S.O.E. and insisted on having a secret French code that only his organization, the Free French, had access to. Leo quietly figured out what this code was and helped himself to all their information before they got it themselves. He is quite funny about pretending to not know about The Secret French Code. It’s a theme that runs through the entire book.

Leo Marks briefed most of the secret agents whose biographies I had already read but his name doesn’t start coming up in books published before the mid-1990s. I suspect that records that weren’t destroyed outright were not de-classified until fifty years after the end of the war, which would be 1995. Between Silk and Cyanide was published in 1998.

Cyanide in the title refers to the cyanide pill that agents were given when they were dropped into occupied countries. The pill was an alternative to being tortured by the Gestapo. Some took that alternative, some didn’t. Some refused to carry the pill at all.

Silk is a little harder to explain. Once an agent was in enemy territory, all communications had to be enciphered and then put into Morse code to be transmitted. The secret agents created codes out of poems that were easy for them to remember –famous quotations or lines from Shakespeare or Tennyson–so they wouldn’t carry evidence of their codes on them. The trouble with this system was that the Germans knew English literature, too, and they had genius cryptographers as well.

Leo first weaned the agents off famous quotations and had their codes created from original verse. He kept a “ditty box” of verses he himself wrote. His most famous verse, used by Violette Szabo who was executed at Ravensbruck, was actually written for his first girlfriend who was killed in the war.

The life that I have
Is all that I have
And the life that I have
Is yours.

The love that I have
Of the life that I have
Is yours and yours and yours.

A sleep I shall have,
A rest I shall have
Yet death will be but a pause;

For the peace of my years
In the long green grass
Will be yours and yours and yours.

But finally after much nuisance, red tape, and offering people valuable books from his father’s shop, Leo managed to push through a system whereby a hundred one-time codes (or ‘worked-out keys,’ WOKs)were printed on silk. Once a line of code had been used in a message to London, the agents cut it off the piece of silk and burned it. The silks were adopted late in the war.

This is a bloody brilliant book. It reads like a detective thriller interspersed with tutorials in coding, which are fascinating in this age of the computer. The human mind is really the first computer and the unconscious is “the greatest of all code rooms.”

Here are some bits that I especially enjoyed:

* It was there on the blackboard, glaring at him. He hadn’t bothered to ask what ‘worked–out keys’ were. He probably thought they were iron-based laxatives. . . I shoved a sample of a WOK at him like a door-to-door salesman and showed him how to use it. . . His expression conveyed to me what he was considering using it for. Even his blackheads seemed to underline in porous italics his silent rejection of everything I’d said.

* He had a particular flair for masonic books and was honorary advisor to the Grand Lodge library, yet he wasn’t Freemason because Catholics were forbidden to join secret societies other than their own.

* Tiltman’s eyes became sheets of calculus at the mention of indecipherables. (Tiltman was head of Bletchley Park)

* Since agents often hid their WT sets in lavatory cisterns, he’d devised a lavatory chain which could act as an aerial. He also had a stock of lethal toilet paper which he hadn’t yet issued because he couldn’t be sure it would be used by the right behinds.

*He was short enough to make me feel average with a moustache which was as clipped as his delivery and eyes which didn’t mirror his soul or any such trivia. . .He had eyes which could lance an abscess, a court-martial of a mouth, and an expression that warned me he had found his next victim. (Description of Colin Gubbins, head of S.O.E.)

* We both stood up. In his case, it showed.

* Aggression was their common denominator and each of them had as much in his make-up as a saint’s unconscious.

* He said something in French which I took to be thanks, shook my hand and de Gaulled out of my office.

* The facts emerged slowly, like soldiers from a brothel.

* Alors, messieurs. . .the message sur the blackboard are from one of your agents. Je suggest that we attackez votre code together.”

* That put the chat among the pigeons.

* A dark-haired slip of mischief rose from behind a desk. (Description of Noot Inayat Khan)