Mavis Batey
The Bletchley Park codebreaker whose decrypt set up the Battle of Cape Matapan.
Mavis Lever (1921–2013) left her language studies and ended up in Dilly Knox's section at Bletchley Park in 1940, where a small team of young women attacked Enigma variants with pencil, paper and intuition rather than Turing's bombes. In March 1941 she read an Italian naval message revealing a planned operation; the intelligence fed into the British victory at Cape Matapan.
With Knox she later broke the Abwehr Enigma, which let the British confirm that their double agents were actually being believed – a precondition for the deception ahead of D-Day. After the war she married fellow codebreaker Keith Batey, became a garden historian, and in 2009 published a biography of Knox.