David studied history at the University of York in England and theology at the University of Wales. Research in the field of religious history (at Cardiff) followed on naturally. He has spent most of his professional life teaching history, most recently in adult education departments within the University of Wales where he has taught a wide variety of courses pertinent to the wider Atlantic world. In 1988, he made his first lecture-tour of the U.S. for the English Speaking Union. He has published extensively on Welsh history and topography–his most recent book being the Companion Guide to Wales (2005)–and is a frequent contributor of articles and reviews to Welsh cultural and literary journals. In the1990s, David was active in the field of international education, traveling worldwide and spending a year in the U.S. (in Atlanta and New York City). He speaks English and French in addition to his native Welsh.
He joined Lindblad Expeditions-National Geographic as a full-time expedition historian in 1998 and has traveled the world in that capacity, from the Arctic to the Antarctic (via Saudi Arabia) and from the Seychelles to Easter Island (via Namibia). He was elected a Fellow of the Royal Geographical Society in 1998 and a Fellow of the Royal Historical Society in 2003.