Report on a fluxgate gradiometer survey, conducted as part of a research project of land off Hagnaby Road, Old Bolingbroke. The survey was conducted to provide context to the finding of an English Civil War helmet in this vicinity, which had been reported to the British Museum's Portable Antiquities Scheme (as PAS object LIN-E0B301). Whilst a number of magnetic anomalies were recorded by the survey, almost all of these were thought to derive from modern disturbance, and no clear archaeological features were identified.