Paul was brought up by his grandparents (whom he took to be his parents) in North West London. He was educated at Lyon Park school in Alperton and Harrow County Grammar School. His undergraduate applications were rejected by the Universities of Oxford, Cambridge, Sussex and York because he did not possess the required foreign language GCE. He was offered a place at the University of Birmingham on the condition that he take French classes in his first year. He received his BSc degree in biology in 1970 from the University of Birmingham and his PhD degree in 1973 from the University of East Anglia for research on "Candida utilis". He then pursued postdoctoral work at the University of Bern, Edinburgh University and Sussex University.