Mavis Lilian Batey, MBE (née Lever; 5 May 1921 – 12 November 2013), was a British code-breaker during World War II. She was one of the leading female codebreakers at Bletchley Park.^[1]

She later became a historian of gardening, who campaigned to save historic parks and gardens, and an author.^[2] Batey was awarded the Veitch Memorial Medal in 1985, and made a Member of the Order of the British Empire (MBE) in 1987, in both cases for her work on the conservation of gardens.^[3]

Mavis Lilian Lever was born on 5 May 1921^[2] in Dulwich to her seamstress mother and postal worker father. She was brought up in Norbury and went to Coloma Convent Girls' School in Croydon.^[4] She was studying German at University College, London at the outbreak of World War II:

I was concentrating on German romantics and then I realised the German romantics would soon be overhead and I thought well, I really ought to do something better for the war effort.^[5]

She decided to interrupt her university studies. Originally, she applied to be a nurse, but discovered that her linguistic skills were in high demand.^[6]

At first she was employed by the London Section to check the personal columns of The Times for coded spy messages.^[7] Then, in 1940, she was recruited to work as a codebreaker at Bletchley Park.^[2] She worked as an assistant to Dilly Knox, and was closely involved in the decryption effort before the Battle of Matapan.^[8][9][10] According to The Daily Telegraph, she became so familiar with the styles of individual enemy operators that she could determine that two of them had a girlfriend called Rosa. Batey had developed a successful technique that could be used elsewhere.^[11]

Although Batey was just 19, she started working on the Italian Naval Enigma machine, and by late March 1941 she effectively broke into their framework, deciphering a message which said "Today's the day minus three". She and her colleagues worked for three days and nights and discovered that the Italians were intending to assault a Royal Navy convoy transporting supplies from Cairo to Greece.^[6][1] The messages they deciphered provided a detailed plan of the Italian assault,^[12] which led to the destruction by an Allied force of much of the Italian naval force off of Cape Matapan, on the coast of Greece. The leader of the Matapan attack, Admiral Andrew Cunningham, later visited Bletchley Park to thank Knox, Batey, and her fellow code-breakers for making his victory possible.^[13]

Apart from being a talented code-breaker (he had broken the Zimmermann Telegram in World War I), Knox was a noted classics scholar, and wrote a poem to celebrate the Allied success at Matapan. He included a stanza dedicated to Batey and the key role she had played in the victory:

"When Cunningham won at Matapan, By the grace of God and Mavis, 'Nigro simillima cygno est,' praise Heaven, A very 'rara avis.' " ("Like the black swan, she is, praise heaven, a very rare bird".) It was, she later said, "very heady stuff for a 19-year-old".^[14]

In December 1941 she broke a message between Belgrade and Berlin that enabled Knox's team to work out the wiring of the Abwehr Enigma, an Enigma machine previously thought to be unbreakable.^[4] Later, Batey broke another Abwehr machine, the GGG. This enabled the British to be able to read the Abwehr messages and confirm that the Germans believed the Double-Cross intelligence they were being fed by the double agents who were recruited by Britain as spies.^[1]

While at Bletchley Park she met Keith Batey, a mathematician and fellow codebreaker, whom she married in 1942.^[2][15]

Mavis Batey wrote a biography of Dilly Knox: ‘Dilly: The Man Who Broke Enigmas’. The book gives a summary of the government codes and cypher school's codebreaking operation in Bletchley Park. It also describes her code breaking of the Italian Enigma which contributed to the British Navy's success at the Battle of Cape Matapan.^[12]

Batey spent some time after 1945 in the Diplomatic Service, and then brought up three children: two daughters and a son.^[16] She published a number of books on garden history, as well as some relating to Bletchley Park, and served as president of the Garden History Society, of which she became secretary in 1971.^[16][17]

She was awarded the Veitch Memorial Medal in 1985, and made a Member of the Order of the British Empire (MBE) in 1987, in both cases for her work on the conservation of gardens.^[18][3]

Batey, a widow since 2010, died on 12 November 2013 at age 92.^[1][4][19]

In 2005, The Gardens Trust held the first Annual Mavis Batey Essay Prize, a competition geared towards international students who are enrolled in a university, institution of higher education or who have recently graduated from one.^[20] The award celebrates Batey's achievements and advocacy in gardening.^[20]

• —— (1982). Oxford Gardens: The University's Influence on Garden History. Avebury. ISBN 978-0861270026.
• —— (1983). Nuneham Courtenay: An Oxfordshire 18th-century Deserted Village.
• —— (1984). Reader's Digest Guide to Creative Gardening.
• —— (1988). Jacques, David; van der Horst, Arend Jan (eds.). The Gardens of William and Mary. London: Christopher Helm. ISBN 978-0747016083.
• —— (1989). The Historic Gardens of Oxford & Cambridge. Macmillan. ISBN 978-0333446805.
• ——; with David Lambert (1990). The English Garden Tour: A View Into the Past. John Murray. ISBN 978-0719547751.
• —— (Spring 1991). "Horace Walpole as Modern Garden Historian". Garden History. 19 (1): 1–11. doi:10.2307/1586988. JSTOR 1586988.{{cite journal}}: CS1 maint: date and year (link)
• —— (1995). Regency Gardens. Shire Books. ISBN 978-0747802891.
• —— (1995). Story of the Privy Garden at Hampton Court. Barn Elms. ISBN 978-1899531011.
• —— (1996). Jane Austen and the English Landscape. Barn Elms. ISBN 9781556523069.
• —— (1998). The World of Alice.
• —— (1999). Alexander Pope: Poetry and Landscape. Barn Elms. ISBN 978-1-89953-105-9.
• —— (2008). From Bletchley with Love. Bletchley Park Trust. ISBN 978-1-906723-04-0.
• —— (2009). Dilly: The Man Who Broke Enigmas. Dialogue. ISBN 978-1-90644-701-4.
• —— (2017). "Breaking machines with a pencil (chapter 11)". In Copeland, Jack; et al. (eds.). The Turing Guide. Oxford University Press. pp. 97–107. ISBN 978-0-19-874783-3.