Mavis Batey (née Lever) was one of the leading code-breakers at Bletchley Park during the Second World War and her work proved crucial to the ultimate success of the allied forces. Later in life she became an author, garden historian and a passionate campaigner for conservation.
She was born in Dulwich in May 1921. At the outbreak of the Second World War she was studying German Romanticism at University College, London. She decided to postpone her studies in order to enlist as a nurse but was told that, given her particular skills, she would be more useful as a linguist.
Initially she worked in London, scrutinising the personal columns of The Times for coded messages. However, she showed great promise and, in early 1940, when she was just nineteen, she was despatched to Bletchley Park in Buckinghamshire, the war-time home of the Government Code and Cypher School. There she worked in the research unit being run by leading code-breaker, Alfred Dilwyn “Dilly” Knox.
Mavis became an invaluable member of Knox’s team and worked on the Italian navy’s Enigma machine. In reconstructing the wiring of the machine, she discovered it had a major flaw and this was a huge breakthrough in deciphering its coded messages. In March 1941, Mavis and her colleagues intercepted messages that revealed Italian plans to attack a Royal Navy convoy which was carrying supplies from Egypt to Greece.
Working solidly for three days and nights, they uncovered full details of these ambush plans, including the exact numbers and locations of the cruisers and submarines involved. This information gave the Commander-in-Chief of the Royal Navy’s Mediterranean Fleet the perfect opportunity to launch a surprise counter attack against the Italian navy. The success of the ensuing battle meant that the Italians made no further attempts on the Royal Navy.
Arguably Mavis’ most vital contribution was to break into the German Enigma machine known as Abwehr and thus contribute directly to the success of the D-Day landings. British forces were using captured enemy spies as double agents to feed false information to the Germans. Unfortunately, without being able to break the Abwehr Enigma, there was no way of knowing if the German forces actually believed the false information with which they were being supplied.
The Abwehr machine had, thus far, proved impenetrable because it had four rotor arms instead of the usual three and, unlike other machines, these arms rotated randomly with no discernible pattern. In December 1941, however, Mavis broke a message which enabled the reconstruction of one of the rotor arms. Within days Knox and his team had broken into the Abwehr Enigma. Shortly after that, Mavis broke a second Abwehr machine, the GGG, further facilitating the British forces’ ability to read high-level coded messages.
From that point on, the British intelligence agencies could be certain that the German forces believed all the information being fed to them. This allowed them to provide a stream of intelligence suggesting that the allies had an entire army preparing to storm the Pas de Calais.
As the allies actually landed in Normandy on 6th June 1944, the false intelligence supplied had implied that the main attack would be in Calais. On receipt of this information, Hitler had ordered two key armoured divisions to remain in the Calais area. Without the breaking of the Abwehr Enigma, the D-Day deception could not have been perpetrated and the landings may well not have succeeded.
Mavis’ husband, Keith Batey, was a mathematician and himself one of the code-breakers at Bletchley Park, which is where the couple met. They married in 1942 and had three children together. Due to the strictures of the Official Secrets Act, neither was able to disclose their work at Bletchley until decades later. Despite her being one of the best government code-breakers (of either sex), the invaluable contribution Mavis had made to Britain’s victory in World War II was classified information and remained a secret, even from her close family, until the 1970s. She quipped that her children had previously wondered at her and husband’s skills as Scrabble players.
Following the war, Mavis began researching garden and landscape history. She became a tireless campaigner for the preservation of historical gardens and she published several books on the subject. She was the president of the Garden History Society from 1985 until her death 35 years later and, in 1987, she was awarded an MBE for her contribution to the conservation of historical gardens. Her books include Jane Austen and the English Landscape, Alexander Pope: Poetry and Landscape and an affectionate biography of Dilly Knox, The Man Who Broke Enigmas.
Mavis Batey died in 2013 aged 92. Historian and Bletchley Park trustee, Michael Smith, said of her, “Mavis was something special and what she did was something special”.