He did work placements at Rothamsted Experimental Station in Harpenden and at Ministry of Agriculture, Fisheries and Food in Liverpool, before studying for a PhD awarded by the University of Strathclyde for researching natural isotopic abundances of elements to enable prediction of soil development when at the Natural Environment Research Council's radiocarbon laboratory, in the Scottish Universities Research and Reactor Centre, East Kilbride.
He worked as a research scientist for the Medical Research Council (MRC) Radiobiology Unit at Harwell in Oxfordshire from 1979-85, where he researched the removal of radionuclides from lung tissue, before becoming Head of Computing for the Mathilda and Terence Kennedy Institute of Rheumatology in Charing Cross (now owned by Imperial College) from 1985-90, building computer systems for the Kennedy Institute (also part of Hammersmith Hospital), the Arthritis and Rheumatism Research Council and Charing Cross Sunley Research Centre. From 1990-1, he was an IT consultant at Pfizer Central Research in Sandwich, south Thanet, where Viagra was discovered, advising research scientists on the design of computer systems, before being working as Head of Computer User Support until 1997.
Ladyman is an active member of Labour Friends of Israel, and has made visits to Israel on a number of occasions. His writings on the Israeli-Palestinian conflict include a Guardian article in support of Israeli attacks against Gaza.
After presenter Richard Hammond was seriously injured in a high speed crash in 2006, Ladyman voiced his support for the program. He denied that Top Gear encouraged dangerous driving, instead that they “celebrate great engineering and, yes, they celebrate fast cars . . . but, equally, they’ve had me on the programme giving out road safety messages. People don’t go onto the road and break the speed limit because they watch Top Gear.” .