The enclosure, which probably dates to the early medieval period, was first identified not on the ground but from the air, when a circular cropmark appeared on an aerial photograph taken in August 1996. Cropmarks of this kind form when buried features such as ditches or banks cause the vegetation above them to grow differently, revealing the ghost of a structure that is otherwise invisible at ground level.

The enclosure occupies a gentle south-facing slope overlooking a river gully to the south, a setting that would have made good practical sense for whoever built it. A fosse, the outer ditch that would originally have defined and defended the perimeter, is still clearly visible as a depression in the ground, and a probable entrance can be made out in the south-east quadrant. The raised circular area at its centre measures roughly 27 metres across on the north-west to south-east axis. At some point before the golf club incorporated the field, someone levelled what had been a more prominent earthwork. Local memory attached a warning to this act: the landowner recalled being told that a fort had stood here, and that the person responsible for levelling it had died shortly afterwards. Whether or not that story shaped subsequent decisions about the site, the golf course construction did modify the immediate surroundings to accommodate tees and greens, though enough of the original form survived to remain identifiable.