The survey was undertaken using four Bartington Grad601 sensors mounted at 1m intervals (1m traverse interval) onto a rigid carrying frame. The system was programmed to take readings at a frequency of 10Hz (allowing for a 10-15cm sample interval) on roaming traverses (swaths) 4m apart. These readings were stored on an external weatherproof laptop and later downloaded for processing and interpretation. The system was linked to a Trimble R8s Real Time Kinetic (RTK) differential Global Positioning System (dGPS) outputting in NMEA mode to ensure a high positional accuracy for each data point, in accordance with EAC guidelines (EAC 2016). The survey has not identified any anomalies of definite archaeological origin. Very faint, short curvilinear anomalies of uncertain origin identified towards the centre of the survey area are most likely natural in origin arising from a more variable magnetic background recorded in this location. It remains possible they could relate to extraction activity recorded on the first edition 25-inch OS map, identifying clay and marl extraction pits in the now wooded areas immediately adjacent the survey area to the east, west and north respectively or even the neighbouring service installation. Two service pipes are identified within the Site, one running along the southern boundary of the parcel parallel to Hall Lane and a second heading north from Hall Lane. Overall, the findings of the survey reflect the limited archaeological potential of the general area which is not recorded as within a RAZ and that was identified in the Historic Environment search conducted for the HS2 Environmental Statement.
Matt Berry (Sat,) studied this question.