It exists, for now, almost entirely as a photograph taken from the air.

In July 1975, an aerial survey captured what archaeologists call a cropmark, the phenomenon where buried features such as ditches or banks cause overlying vegetation to grow differently, revealing their shapes to a camera looking straight down. The image, catalogued as GSIAP R528-9, showed three sides of a rectangular enclosure: a bank with an external fosse, which is a ditch dug on the outer face of a defensive or boundary earthwork, running along the south-west, north-west, and north-east. The south-east side was unclear in the photograph, and may have been intentionally open, suggesting an entrance or simply an unenclosed edge. Beyond what the cropmark itself shows, little else is known about the structure: its date, its function, and who built it remain unrecorded.