Having completed a traineeship in General Practice in the UK, David returned to Blackrock Co Dublin in 1970 where he joined Dr John Goodbody and Dr Robin Benson in setting up one of the first Irish Group Practices. He acted as managing partner for a period of fifteen years. From 1985 he worked in Trinity College Dublin as the Director of the College Health Services and as lecturer in the Department of Primary Care and Community Medicine. He was also Medical Director of Bloomfield Hospital Donnybrook from 1990 to 2005. Since his retirement from Trinity in 2010, he has remained actively involved with the Medical Council, with Irish College of General Practice serving on several committees and was instrumental in founding the Retired General Practitioner Discussion Group.