Ogham is an early medieval Irish script, typically carved as a series of notches and strokes along the edge of a standing stone, and this particular example reads along its north edge as it currently sits, which means the inscription runs sideways, embedded into masonry, largely inaccessible to the eye. On either side of it, set into the same rebuilt southern wall of the chancel, are a crucifixion plaque and an architectural fragment, so the stone sits in peculiar company, wedged between objects from entirely different periods and purposes.

The inscription has been read in two slightly different ways by scholars working at different times. R.A.S. Macalister, writing in 1945, transcribed it as BRRUANANN, while Damian McManus, revisiting it in 1997, preferred BRRENANN. Both readings point toward a personal name, likely commemorating an individual in the early Christian period when ogham was in active use. A 1939 Ordnance Survey map marked the site of an ogham stone approximately fifty metres south-southwest of the church ruins, which raises the question of whether the stone now embedded in the wall is the same one, moved and repurposed at some point during rebuilding work. The matter is complicated further by a second ogham stone, now lost, which was found lying in the northwest corner of the church in the early nineteenth century. Whether the two stones were ever distinct objects, or whether the same stone was recorded twice at different moments in its wandering history, has not been resolved. The stone has been examined as part of the Ogham in 3D project run by the School of Celtic Studies at the Dublin Institute for Advanced Studies, which used digital scanning to document ogham inscriptions across Ireland.