Supreme code-breaker

By Maggie Hartford »


Mavis Batey (Dialogue, £19.99)

Mavis Batey is known in Oxford as a conservationist and expert on garden history, but her latest book is about her wartime boss at Bletchley Park, Dilly Knox, the code-breaker who helped to break the Nazis’ secret ciphers.

A brilliant but absent-minded man, he had been known to stuff his pipe with sandwiches rather than tobacco, and forgot to tell his brothers that he was getting married.

Born in 1921, the young Mavis was due to study German at University College, London, when the Second World War broke out. Her language skills meant she was assigned to the Foreign Office and sent to Bletchley Park, centre of the code-breaking operations which were crucial to the Allied victory.

Her book portrays Knox as the most brilliant cryptologist of his day, who never received the recognition of his colleague Alan Turing.

Before the war, he had broken Bolshevik ciphers and reconstructed the mimes of Greek poet Herodas from fragments of papyrus uncovered by archaeologists.

She plays down her own contribution at Bletchley Park, but it included cracking the Italian code, with the help of a pocket dictionary, to reveal a message: “Today’s the day minus three.” With the code broken, ‘Dilly's girls’, as they were known, were able to deduce the complete battle order of an Italian fleet threatening a British convoy in the eastern Mediterranean.

At Dilly’s insistence, a reconnaissance plane was sent out to “spot” the oncoming fleet, which was destroyed at the Battle of Matapan.

Despite being ill with cancer, he masterminded the cracking of the Germans’ Enigma code machine, allowing the Allies to send coded messages hoodwinking them into thinking that British troops were preparing to invade Calais from south-east England.

This diverted attention from the real plans for D-Day landings in Normandy.

After the war, Batey and her colleagues — including her husband Keith, whom she met at Bletchley Park — were unable to talk about their secret work for more than 30 years.

She moved to Oxford in the 1960s with her husband, treasurer of Christ Church, and made a career in conservation and garden history, inspired by their home in Nuneham Courtenay.

Now in retirement on the South Coast, she has recently been in demand from researchers wanting inside information on what it was like to be a woman Bletchley — including actress Kate Winslet, who starred in the film Enigma.

Her biography of a “brilliant, humane, intuitive, if eccentric, genius” is characteristically meticulous, and she does her best to explain the crossword-type clues that allowed ‘Dilly's girls’ to crack the problems.