John is Professor Emeritus of Cell and Molecular Biology at the University of Exeter. His research focussed mainly on the control of DNA replication. He has published well over 100 academic papers and reviews and 28 books. He is also active in communicating science to a wider public through the British Science Association, Café Scientifique Christians in Science and via the broadcast media. He is a Fellow of the Royal Society of Biology, a member and former President of the Society for Experimental Biology, and a member and former regional Chair of the Biochemical Society.
He also introduced Bioethics into the Bioscience curriculum at Exeter and for several years was one of three advisers to the Higher Education Academy on Teaching Ethics to Bioscience students