Two of them turned out to be recycled ogham stones, ancient inscribed monuments that had been quietly doing structural work for centuries, their carved edges pressed into service long after anyone nearby could read them.

Ogham is an early medieval script, mostly found in Ireland and parts of Wales and Scotland, in which letters are represented by groups of notches and strokes cut along the edge of a stone. The south-west pillar at Ballynabortagh is a rough, irregularly shaped sandstone column, roughly 1.5 metres tall and subrectangular in cross-section, with its inscription running along the right angle of one of its narrower faces. The carved section is confined to the lower, narrower portion of the stone, and much of the text has been lost. What survives produces a fragmentary reading of something like (L)……C(A)……CIOT, which at first appears to offer nothing useful. Scholars working on the inscription have proposed, cautiously, that the damaged text may follow the MAQI MUCOI formula, a standard phrasing in monumental ogham meaning "son of a remote ancestor", giving a tentative reconstruction along the lines of L……[MA](Q)I [MU]COI T…. The north-east pillar in the same souterrain also carries an ogham inscription, suggesting that whoever repurposed these stones for roof supports had access to at least two carved monuments, whether deliberately chosen or simply to hand.

The Ballynabortagh stone is a reminder that ogham inscriptions rarely survive in their original context. Many were moved, broken, built into walls, or, as here, pressed into underground architecture. The partial legibility of this example is not a failure of the inscription so much as a record of everything that happened to it in the intervening centuries.