Walker was born on January 7, 1941, in Halifax, England. In 1960, he enrolled at St. Catherine's College, Oxford, and was awarded his B.A. in chemistry by St. Catherine's in 1964. Walker then spent four years as a research student at the Sir William Dunn School of Pathology at Oxford before earning his M.A. and D. Phil. degrees from Oxford in 1969.

Upon completion of his doctoral studies, Walker spent two years as a postdoctoral fellow at the School of Pharmacy at the University of Wisconsin. He then spent three additional years as a NATO Fellow at CNRS, in Gif-sur-Yvette, France, and as an EMBO Fellow at the Institut Pasteur in Paris. In 1974, Walker accepted an appointment as a member of the scientific staff at the Laboratory of Molecular Biology of the Medical Research Council in Cambridge, England.

Adenosine triphosphate (ATP) is one of the most important molecules in the cells...