Alan Nunn May was born on 2nd May 1911 in Moseley, Warwickshire [incorporated in Birmingham that year] (United Kingdom), the youngest of four children to Walter Frederick and Mary Annie Nunn May (née Kendall). His grandfather, father, and eldest brother (Edward) worked as brass founders in the family firm. In 1921, Alan lived in Bromsgrove, Worcestershire with his father, mother, brothers Edward and Ralph (metallurgical student), and sister Mary (in full time education). The family firm collapsed sometime after 1921 and this led the family to move to a smaller house, and Alan received a scholarship at King Edward's School.

Alan Nunn May was educated at home (by governesses and the local vicar), then at King Edward's school in Birmingham (1924-1930), and the University of Cambridge (1930-1933) where he was awarded a scholarship at Trinity Hall and took part I of the Maths Tripos and part II of the Natural Sciences Tripos in Physics. He then undertook a PhD in the Cavendish Laboratory (University of Cambridge), went on to a junior lectureship at King's College London (1936-1939), then began a training scheme for physicists to learn about radar in the Summer of 1939 but was recalled to join King's College London teaching staff who had been evacuated to Bristol.

Whilst teaching in Bristol, Alan joined Cecil Powell's research project on a photographic method for measuring particles from radioactive substances (Oct 1939). In Spring 1942 he was asked to join Hans Halban and Lew Kowarski's research group at the Cavendish Laboratory in Cambridge who were part of the nuclear weapons research and development programme code-named Tube Alloys. He then went with colleagues from Cambridge to Canada to work in the Montreal Laboratory for the project (1943-1945).

In 1936 Alan had joined a Communist Party group in London and visited the Soviet Union. He was part of the Association of Scientific Workers and the Left Book Club Scientists Group. In 1942 Alan made contact with a Russian diplomat in Cambridge [via his Communist Party group] and shared a memorandum he had written on the current status of the nuclear project and what was planned by the United Kingdom and United States. The [Communist] group leader then instructed Nunn May to set up a centre for sharing information when he got to Canada.

During 1945 Alan was contacted by a Russian agent in Canada and started sharing summaries of the nuclear research projects and copies of official reports. Unknown to Alan, Igor Gouzenko (a cipher clerk in the Soviet embassy to Canada) defected in September 1945 with incriminating material that led the authorities to Alan. The decision was made not to arrest Alan in Canada, but rather to let him return to the United Kingdom with the hope he would reveal his Soviet contacts.

On Alan's return to London (as acting Head of Department at King's College London) he was followed by the Secret Service for several months, and was finally arrested in March 1946. He was held on remand in Brixton Prison and appeared at the Old Bailey court on 1 May 1946. He pleaded guilty to the charge of breaking the Official Secrets Act and was sentenced to ten years in prison, of which he served less than seven (being released at the end of 1952).

Alan married Dr Hildegard Broda (née Gerwing) on 2 Aug 1953. The couple adopted a six-week old baby, John, in 1954, who joined them and Hilde's son (Paul Broda).

At the end of 1953 Alan Nunn May began working in Nora and Peter Wooster's private laboratory in Cambridge (Brooklyn Crystallography Laboratory/Crystal Structures Limited) on instrument design and metal fatigue. His work at the laboratory was funded via an anonymous donor (now known to be the Government) who sent payment through Cambridge University.

In 1961 Alan was invited by Ghanaian President Kwame Nkrumah to go to the University of Ghana as a Research Professor, which he accepted, and he became Head of Physics in 1963. As well as research and teaching, Nunn May was involved with starting a science museum. He retired from the University in 1976, then was a government advisor on science education (1976-1978). In 1978 Alan and Hilde returned to live in Cambridge.

Alan Nunn May died in Cambridge on 12 January 2003.