My first degree was in physics and chemistry and included a year in the US doing physics and philosophy. Having worked in computing I did the MSc in Medical Statistics at LSHTM and worked in statistics and computing at The London Hospital and Medical College for 25 years, leaving there in 1995 as Prof of Medical Statistics, and was made Hon. Prof at LSHTM. I was then at the UK Medicines Control Agency (now MHRA) and briefly at Quintiles where I mainly worked on the Bristol Royal Infirmary Inquiry. I joined LSHTM part-time on retirement in 2002. I was (until June 2018) a European Commission appointed independent Expert member of the Pharmacovigilance (Drug Safety) and Risk Assessment Committee at the European Medicines Agency. I was President of the International Society of Pharmacoepidemiology for 2010/2011. From October 2022 I am Emeritus and do not act as a supervisor of PhD students.

I am the statistician to the CEPI meta-Data and Safety Monitoring Board overseeing all trials of vaccines funded by CEPI for disease mainly affecting low and middle-income countries. I continue with minor involvement in the OpenSafely collaboration. I was convenor of the Statistics Expert Group at the Infected Blood Inquiry which reported in May 2024. I wrote an expert report for, and appeared at the UK Covid Inquiry on vaccine safety.