Gabriel studied at Cambridge University as an undergraduate and doctoral student, and at the Courtauld Institute of Art for his master's degree. He has published widely on Medieval and Early Modern parish church architecture. His most recent article, in the Journal of the British Archaeological Association, won the Reginald Taylor and Lord Fletcher Prize. Subsequently, he has worked for the Churches Conservation Trust, Cambridge Architectural Research Ltd. and Donald Insall Associates, and runs the ChurchGuides.co.uk website. He lives and works in London.