Bill qualified in medicine in 1980, and initially worked as an anaesthetist.  He joined the pharmaceutical industry in 1987 and worked for 15 years in Medical Affairs, Clinical Development, and Pharmacovigilance in Europe and the UK.  He joined the Medicines Control Agency (now MHRA) in 2002 and became a senior medical assessor for pharmacovigilance and risk management. He left the MHRA in 2014 to become a pharmacovigilance consultant.