His interest in pediatric infectious diseases was sparked by two years working in the Himalayas for Save the Children Fund UK. He has specialised in HIV infection in children since 1989, as a Fellow at Duke University, N. Carolina (with Prof. Cathy Wilfert), and as a Visiting Scientist / Attending Physician at the National Institutes of Health, Bethesda, MD (with Prof. Phil Pizzo).
Since 1994 he has helped run a multi-disciplinary service for HIV infected children and their families at St. Mary's Hospital, London.
Academic roles: founding Chairman of the Children’s HIV Association of the UK and Ireland (CHIVA). Involved in clinical trials with the Pediatric European Network for the Treatment of AIDS (PENTA). Co-principal investigator for the PENTA/IMPAACT study - PENPACT 1. Chair of the End-point Review Committee for the ARROW trial of 1200 HIV-infected children (Uganda / Zimbabwe). Helped establish the CHIVA-Africa initiative, supporting the roll-out of antiretrovirals for children in S. Africa. Trustee of the UK Thailand Children’s Fund, supporting HIV affected children in northern Thailand.