Is a qualified general consultant physician in general medicine and clinical pharmacology, and has held professorial posts in both subjects, in Zimbabwe, New Zealand and Sweden.
In New Zealand he was Director of the National Toxicology Group and had 10 years experience in drug regulation and pharmacovigilance as Medical Assessor for the Medicines Adverse Reaction Committee and the Medicines Assessment Advisory Committee. He also had similar responsibilities to the New Zealand Toxic Substances Board for the registration of other chemicals and for advice on chemical safety.
He was Chairman of the Advisory Committee to the WHO Programme for International Drug Monitoring.
For his last 25 years of full time working he was the foundations Director of the Uppsala Monitoring Centre, which is responsible for the technical support to all WHO supported drug safety monitoring programmes worldwide. He was the first to develop data mining in pharmacovigilance and risk-benefit analysis. He still works in research mainly on issues of causation evidence, following an interest in philosophy of science. He is an Editor-in-Chief of the International Journal of Risk and Safety in Medicine
He was the first President of the International Society of Pharmacovigilnce (ISoP) as it developed from the European Society of Pharmacovigilance (ESoP) of which he was a founding member.
Over 35 years of working with pharmacovigilance issues, he has appeared as an expert witness in several jurisdictions; in the UK, New Zealand, the USA and Hong Kong.
He has written/co-written over 400 scientific papers.