What the photograph captured was a set of cropmarks, the faint differential colouring that appears in growing crops when buried features beneath the soil affect how plants above them develop. Ditches and filled-in earthworks retain moisture differently from undisturbed ground, and in dry conditions that contrast becomes readable from the air in a way that is almost entirely invisible at ground level.

The photograph, taken on 9 July 1964 as part of the Cambridge University Collection of Aerial Photography, recorded a circular enclosure defined by what appears to be the cropmark of a fosse, the term for a ditch typically dug around a settlement or monument for drainage or defence. To the south-west of this enclosure, a series of linear ditches emerged in the same image, suggesting the remains of a field system that may once have been laid out in relation to the enclosure itself. Some of the cropmarks visible in the photograph could be matched to field boundaries that were still upstanding when the first edition Ordnance Survey six-inch map was made in 1839, meaning that at least part of this ancient organisation of the land survived as earthworks well into the nineteenth century before disappearing from the surface entirely. The 1839 OS mapping provides a useful anchor: features visible then as physical banks or ditches had, by the mid-twentieth century, been levelled, leaving only their subsurface traces to register in crops on a warm July afternoon more than a century later.