The crest carved at its top shows a swan holding a label in its beak inscribed with the words VITA VAPOR, life is vapour, a phrase drawn from the Epistle of James, and beneath the heraldic shield runs the motto VIVANT IN AETERNVM, may they live forever. The tension between those two sentiments, one deflationary, one hopeful, is the kind of thing that rewards a slow look.

The plaque commemorates John Bryan, a gentleman recorded as the son of one Lodavicus, who died on 29 August 1607, and his wife Margaret Walsh, who died on 13 August 1610. The stonework displays impaled arms, meaning two coats of arms joined on a single shield to represent a marriage alliance, combining the Bryan arms of Jenkinstown with those of the Walsh family. The slab is fossiliferous limestone, meaning the stone itself contains the faint impressions of ancient marine organisms, and the inscription is carved in false relief black letter, a style of lettering that mimics the appearance of raised letters by cutting the surrounding surface rather than the letterforms themselves. The plaque was probably once part of a chest tomb, the kind of free-standing memorial with a flat top slab supported on decorated side panels, though it may always have been intended as a wall-mounted mural plaque. It is set within what is described as the Bryan vault, which is in reality a mausoleum adjoining the eastern wall of the south transept. This structure was likely formed by adapting part of the medieval Lady Chapel of St Mary's during the eighteenth century, so the monument sits within a later re-use of a much older sacred space.