Alfred Gavin Maddock was born in Bedford Park, London in 1917. He was educated at Latymer Upper School in Hammersmith and the Royal College of Science, part of Imperial College, London University, where he studied chemistry. He gained a PhD for work on silicon hydrides in 1942.

In 1941, he was working with a group of French scientists who had escaped from Paris at the Cavendish Laboratory in Cambridge. He moved, in 1943, to the Montreal Laboratory in Canada, where he was involved in the design of the nuclear reactor at Chalk River in Ontario. He returned to Britain to work at the Atomic Energy Research Establishment at Harwell, 1945-6, where he helped design the new Radiochemical Laboratory. He then returned to the University of Cambridge, where he was based for the rest of his career, becoming a Reader in Radiation Chemistry, from 1960. He was a Fellow of St Catherine's College, Cambridge, and the President of that College, from 1981.

The Royal Society of Chemistry awarded him the Becquerel Medal in 1996.

He died in Cambridge on 5 April 2009.