Mavis Lever was born 5 May 1921 in Dulwich, South London; daughter of Frederick Lever, a postal worker, and Lily Lever, a seamstress. She was educated at the Convent of Ladies of Mary, in Croydon and then at University College London where she read German.

During the Second World War, she worked as a codebreaker, having been sent to the Government Code and Cypher School. She initially worked in London, checking commercial codes and reviewing the personal columns of The Times for coded spy messages. She was then sent to Bletchley Park to work in the research unit run by Dilly Knox breaking German Enigma codes, notably in March 1941 deciphering a message about an Italian attack on a Royal Navy convoy and breaking the Enigma cipher used by the German secret service, the Abwehr, in December 1941. In 1942 she married (John) Keith Batey, who also worked at Bletchley Park, with whom she had one son and two daughters.

After the war, Mavis Batey became interested in the preservation of historic gardens, working with the Campaign for the Protection of Rural England, English Heritage and the Garden History Society. Working with the Historic Buildings Council, she instigated the formal recording of historic gardens which led to the publication of English Heritage's Register of Parks and Gardens of Special Historic Interest in England in 1984. She had taken a leading role in the Garden History Society since 1971 when she became its Secretary, and was its president from 1985 until 2000. She was also a Tutor in the Oxford Department of External Studies (1970-92).

Batey was awarded the Veitch Memorial Medal of the Royal Horticultural Society in 1985, and in 1987 was appointed MBE for services to the preservation and conservation of historic gardens.

Batey's publications included: Alice's Adventures in Oxford (1980); Oxford Gardens (1982); Historic Gardens of Oxford and Cambridge (1989); (with D. Lambert) The English Garden Tour (1990); Arcadian Thames (1994); Privy Garden at Hampton Court (1995); Regency Gardens (1995); Jane Austen and the English Landscape (1996); Alexander Pope: the poet and the landscape (1999); (jointly) Indignation! (2000); editor A Celebration of John Evelyn (2007); and Dilly: the man who broke Enigmas (2009).

Mavis Batey died on 12 November 2013.