Projecting some 0.3 metres inward from beneath the inner face of the wall is a stone plinth, roughly eleven metres long and about 0.4 metres high, formed from two courses of what looks like drystone construction. It does not appear on the outside of the wall at all. A feature that announces itself on one face and vanishes on the other tends to suggest that it was already there before the current wall was built around or over it.

The question of what exactly it represents has never been settled. The site was catalogued as a possible enclosure in both the 1991 Sites and Monuments Record and the 1996 Record of Monuments and Places, though even the origin of that designation is uncertain. The most plausible explanation traces back to the 1838 Ordnance Survey Letters, a series of detailed field observations compiled by surveyors and antiquarians as part of the great nineteenth-century mapping project. The relevant passage, quoted in a 1927 publication by O'Flanagan, notes that a section of the graveyard's northeast wall appeared to be of ancient construction. If that observation is what prompted the later classification, then the formal record rests on a single cautious remark made nearly two centuries ago. The current interpretation, still hedged with uncertainty, is that an earlier enclosure wall, perhaps predating the graveyard as it now stands, was absorbed into the later structure and survives only as this interior plinth, hidden in plain sight along the inside of the north boundary.