He ran the Newcastle office of the Royal Commission on the Historical Monuments of England (RCHME) which recorded and analysed archaeological sites and historic landscapes throughout the northern counties, including Cumbria.
Subsequently he had a national responsibility as the Director of Architectural and Archaeological Survey within RCHME, and he took this role (in an expanded form) into English Heritage when the two organisations merged. Latterly he was the English Heritage Planning and Development Director for the North (comprising the North West, the North East, and Yorkshire), leading the teams that administered grant schemes and that provided advice within the planning system to local authorities, owners, and developers.
He retired in 2011.
Humphrey is the Chair of the Fabric Advisory Committee (FAC) of Durham Cathedral, a member of the FAC for Carlisle Cathedral, a member of the Carlisle Diocesan Advisory Committee, a trustee of the Historic Chapels Trust, and a Visiting Fellow in the School of History, Classics, and Archaeology in the University of Newcastle.
Until 2018 he chaired the Hadrian’s Wall World Heritage Site Partnership Board and still leads the Wall to Wall programme of collaboration with The Great Wall of China that he initiated.
He has published widely, both in popular books (including three for children) and in specialist papers, and has contributed the archaeological sections of six volumes, covering the northern counties, in the Pevsner Guides to the Buildings of England.
A Fellow of the Society of Antiquaries, he lives in Burgh-by-Sands, near Carlisle.