What had once been a circular earthwork, roughly 32 metres across with its entrance oriented to the south, was gone from the ground by 1970, erased by levelling. Only from altitude did it betray itself, as a cropmark of a fosse, the buried ditch beneath the soil causing the vegetation above it to grow fractionally differently, just enough to register on an aerial photograph taken on 14 July 1970.

The site had been recorded on the first edition Ordnance Survey six-inch map, surveyed between 1839 and 1840, and it was still marked on the 1945 to 1946 revision, which suggests it survived in some form, or at least in cartographic memory, for over a century after the surveyors first noted it. A fosse, in this context, is simply the encircling ditch that would have defined and defended the interior of such a ringwork, the excavated earth typically thrown inward to form a bank. Writing in 1981, Doyle described the circular outline as still relatively easy to trace on the ground, with a discernible southern entrance. What makes the Brownstown site particularly interesting now is what satellite imagery has since revealed: a larger enclosure sits immediately to the east, either joined to it or, more intriguingly, predating it entirely. Whether the two were part of a single complex or represent different phases of activity on the same patch of ground remains unresolved.