Bill was born in Glasgow and undertook his first degree at the University of Glasgow. He subsequently performed his PhD studies in the group of Professor Murray Selkirk at the Imperial College of Science, Technology and Medicine, University of London on characterizing human immune responses against antigens from the filarial nematode brugia malayi. Bill went on to perform his postdoctoral research at the Aaron Diamond AIDS Research Centre, Rockefeller University, New York, where he focussed on studying host factors that can be associated with HIV-1 transmission. Notably, through studying individuals highly exposed to HIV-1 but who remained seronegative identified that the CCR5 chemokine receptor functioned as one of the main co-receptors for HIV-1 infection and that individuals homozygous for a 32bp deletion within the CCR5 gene are highly resistant to HIV-1 infection. His faculty career was conducted at the Academic Medical Centre, University of Amsterdam where he continued to work on HIV-1 and conducted in close collaboration with Dr Georgios Pollakis. The research over those years encompassed the study of viral genotypes and phenotypes associated with transmission (including mother to child transmission), specific properties of subtype C viruses, which cell-types are infected early in infection and identifying host factors from human milk and semen which can interfere with virus transmission. More recently, the lab has initiated studies on better understanding co-pathogen interactions between helminthic parasites, TB and HCV with HIV-1.