Strong archaeological evidence exists for the presence of Anglo-Saxon settlement at the former Roman civitas capital Venta Icenorum, including two cemeteries of early Saxon date. A large-scale magnetic survey west of the former walled town has revealed a complex palimpsest of surviving subsurface features, several of which were cautiously interpreted as the remains of Anglo-Saxon sunken-featured buildings (SFBs). Targeted earth resistance measurements enhanced the interpretation in terms of likely subsurface morphology. One of these anomalies was subsequently subject to archaeological excavation, revealing the surviving remains of an SFB of middle Saxon date. The magnetic susceptibility of deposits sampled during excavation was also evaluated and a simple forward model constructed to compare a theoretical magnetic response of the structure to that observed in the field. A reasonable correlation was observed, allowing the quantitative characterization of similar magnetic anomalies revealed in the survey data. Copyright © 2013 John Wiley & Sons, Ltd.