Leo Marks
Tuesday January 23rd 2001
LEO MARKS, who has died aged 80, was the chief cryptographer of Special
Operations Executive during the Second World War; later he wrote the script
for Peeping Tom, the film which destroyed the career of its director Michael
Powell.
Between 1942, when he joined SOE, and 1946, when he rejected an offer of
employment from MI6, Marks proved himself a code-maker and breaker of rare
genius.
While still in his early twenties he revolutionised the construction and
security of SOE's cyphers. And by his re-invention of the "one-time pad"
he eventually influenced code systems used by secret services the world
over.
In the latter stages of the war he was entrusted with devising encryption
systems for, among others, the SAS and the Free French. Unbeknown to the
latter, Marks had already cracked General de Gaulle's private cypher in
a spare moment on the lavatory.
He began his career as a cryptographer at the age of eight in his father's
antiquarian bookshop in London, Marks & Co, later the subject of Helen Hanff's
memoir 84 Charing Cross Road (1971).
One morning his father Benjamin showed Leo a first edition of The Gold Bug
by Edgar Allan Poe, which he had just bought for £6 10s. Knowing that it
would interest American collectors, he intended to price it at £850.
The book's tale of hidden treasure the whereabouts of which was concealed
by a cypher entranced Leo, and he set about breaking his father's own secret
pricing code, a series of letters pencilled inside the cover of each book.
Within minutes he had found the key (the 10 letters of Marks Cohen, the
two partners in the business, each corresponded to a number) and gained
two ambitions: to become an expert on codes and, like Poe, to write horror
stories.
In January 1942, Marks was called up and went to Bedford to train as a cryptographer,
an opening secured for him by a godfather in Special Branch.
He was the only one of his intake not to be sent on to Bletchley Park; instead,
having in an evening cracked a code intended to be spread as a group exercise
across a week, he was labelled a misfit and dispatched to Baker Street,
the headquarters of the recently formed Special Operations Executive.
Marks almost contrived to fail his interview, taking all day to break a
cypher that he had been expected to decode in only 20 minutes with the help
of a key. SOE's head of codes had forgotten to give him the necessary piece
of paper, and in his memoir Between Silk and Cyanide (1998) Marks drew a
vivid and often angry portrait of an organisation capable of both brilliance
and lethal carelessness. It was also one in which Marks, as a quick-witted
Jew, often felt an outsider.
The title of his book referred to the new codes Marks had devised and had
had printed on silk squares, and the poison carried by agents - life and
death. He had had to come up with new cyphers because when he inspected
SOE's methods for communicating with its agents in the field he was horrified
to discover that the traffic could be read by the Germans with ease.
The agents were using well-known poems as the cyphers for encoding their
messages, and these could either be guessed by an enemy armed with reference
books, or simply tortured out of captured operatives.
His initial solution was to use original poems instead as cyphers. Many
of these he wrote himself, the best known being that which he gave to the
agent Violette Szabo, The Life That I Have. He had actually written it for
a girl with whom he was in love, the news of whose death in an air crash
he heard on Christmas Eve 1943.
The poem was subsequently used in the film made about Violette Szabo, Carve
Her Name With Pride (1958), and generated an enormous response.
Marks took great pains to get to know the agents he briefed, among them
his close friend Forest Yeo-Thomas - "The White Rabbit" - and Noor Inayat
Khan, who suffered from the handicap for a spy of having been brought up
never to lie.
It could be difficult, as happened to Marks, to brief a man and then hear
two days later that the Gestapo had tortured him horribly. But it was vital
for him to understand the temperament of each agent, as this helped him
with the other important area of his work, deciphering the garbled messages
transmitted by agents under stress.
It was vital that any such "indecipherables" - up to 20 per cent of the
daily traffic - should be read as quickly as possible so that, with the
Gestapo on the prowl, the agent need not risk his life to resend it.
As Marks knew the coding idiosyncrasies of each agent - an inability to
spell a certain word or a habit of transposing two columns in a cypher -
he was often able to decipher the signals himself, but he also recruited
400 young women from the First Aid Nursing Yeomanry (Fany) to help him break
indecipherables.
When interviewing these girls Marks did not look for mathematical ability
but for an interest in music and an aptitude for crosswords, believing these
were better pointers to cryptographic talent; he himself was already regularly
setting crosswords for The Times.
Marks's helpers, based at Grendon Underwood in Buckinghamshire, proved immensely
proficient and dedicated. One message was deciphered with seconds to spare
after 650,000 separate attempts.
It was the lack of indecipherables in the traffic of SOE's Dutch section
which first alerted Marks to the so-called Englandspiel, the most serious
disaster to befall SOE.
Marks deduced that since no signals from Holland were ever corrupted, the
Germans must have penetrated the network and be controlling the transmitters.
He was right, but his suspicions fell on deaf ears - or on those playing
a longer game - and up to 50 Dutch agents went unnecessarily to their deaths.
Thereafter Marks concentrated on perfecting codes that could not be discovered
by the Germans. His solution was simple and brilliant - to use one-off cyphers,
printed on silk which the agent then cut away and burnt so that he could
not remember them.
These "worked-out keys" not only reduced the incidence of garbling but,
being random in origin, were much harder for the Germans to crack. Silk
also had the advantage of being easily hidden in the lining of clothes,
and if they were caught each agent was given a method of letting SOE know
that he was transmitting under duress.
By D-Day, when SOE's agents tied down thousands of German troops, Marks's
silks were being used from Normandy to Sarawak. They were particularly gratefully
received by the Free French, who routed all their traffic through SOE, allowing
Marks to read politically sensitive material destined for de Gaulle.
By then he had also refined the one-time pad, first invented by the Germans,
in which a code was made by adding to numbers representing set phrases another
pre-agreed series of numbers. The only copies of these were held by the
agent and his masters, and used just once.
Marks, who needed no invitation to demonstrate his intelligence, adapted
the system to use letters instead of numbers, an idea already being used
independently at Bletchley.
But Marks's drive and determination ensured that the code became widely
disseminated within the British secret services, and in time it became standard
cryptographic technique.
He retained discreet informal links with the Intelligence Service after
the war and devised several other important new types of code; indeed, so
central did his wartime work remain to modern cypher practice that he was
unable to disclose much of it in his autobiography, the publication of which
was delayed by the authorities for more than a decade after he had completed
it.
Leopold Samuel Marks was born in London on September 24 1920. An only child,
he was educated at St Paul's and then helped out in his father's shop, where
customers included Charlie Chaplin, Aleister Crowley and Sigmund Freud.
After the war, Marks turned to writing for the stage and screen, and had
some success in the West End with plays such as The Girl Who Couldn't Quite
(1947) and The Best Damn Lie (1957), which made use of a lie detector.
Indeed much of his literary work, which in truth was largely forgettable,
seemed to hark back to his previous career. Thus the film Cloudburst (1951)
was about a vengeful codebreaker; Sebastian (1967), with John Gielgud, concerned
an academic code expert turned spy.
Quite different from all these was Peeping Tom (1960). At its most superficial,
it is the shocking story of a man, terrorised as a child by his father,
who grows up obsessed with fear. He gets his kicks by filming young women
as he murders them with a blade concealed within his camera.
At a deeper level, the film is a meditation on the voyeuristic nature of
cinema. Since the man's crimes are seen by the audience through his lens,
they are in effect asked to identify themselves with his murderous acts.
Marks's notably intelligent script, influenced by his lifelong interest
in psychoanalysis, contains a number of in-jokes, notably that a director
in the film is played by the blind actor Esmond Knight, and that the name
Leo Marks gave his protagonist was Mark Lewis.
Although now recognised as a strange but serious work, at the time the film
proved too disturbing for audiences and critics. It was described as "evil
and pornographic" and the reaction against it ended the illustrious career
of its director, Michael Powell.
Marks went on to work with the Boulting Brothers, whom he also almost finished
with another film about a homicidal maniac, Twisted Nerve (1968). He never
again reached the heights of Peeping Tom. So provocative is its reputation
that it was not possible to show it on British television until 1997.
The film is the primary influence on the cinema of the director Martin Scorsese;
he acknowledged his debt in 1988 when he asked Marks to play the voice of
Satan in his similarly controversial The Last Temptation of Christ.
Marks's father died in 1968, but he was not tempted to take over the shop,
living instead quietly in west London. He was good company, enjoyed showing
that he knew more than he said, but kept secrets as well as any man. Though
a natural cynic, he was also a romantic.
In person he was short and powerful, with a grip of iron and a voice like
new velvet. He was an habitue of the Special Forces Club.
He married, in 1966 (dissolved 2000), the portrait painter Elena Gaussen.
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