The slab belongs, in a sense, to an older building altogether: the nave of Holy Trinity was once the nave of the medieval parish church of St John the Baptist, and the slab itself is set into the base of a 13th-century tomb niche in the north wall of what was formerly the chancel. It is an object that has been layered over, repurposed, and partially erased by subsequent centuries, yet it survives.

The limestone slab measures at least 1.7 metres in length and 0.42 metres in width. Carved in relief at its centre is a three-armed banded cross, a form in which horizontal bands divide the arms, with fleur-de-lis terminals at each visible end. The upper fleur-de-lis is hidden behind the Palliser vault. Beneath the crossing band, the shaft carries a three-barred knop, a decorative boss-like feature common in medieval funerary carving, and rises from a simple curving calvary mount, the small stylised hill that in Christian iconography represents Golgotha. Along the sinister border, that is the left-hand side as you face it, and continuing along the chamfered edge, runs a Latin inscription in Black Letter script, the angular lettering associated with late medieval and early modern stonework. The text appears to read: EQO DORMIO ET COR MEUM UIGILAT CAM 5 ME FIERI FECIT D PAUL HAKET DICATUIS FID 1643. The opening phrase, a variation on a line from the Song of Solomon, translates roughly as "I sleep but my heart is watchful." The slab was commissioned in 1643, and the name recorded is D. Paul Haket, with the remaining words only partially legible. The date itself is arresting: 1643 places this stone in the middle of a period of profound upheaval in Ireland, and yet here is someone arranging a careful, formally inscribed memorial in the old tradition.