The knight and the lady were sculpted in absentia, commemorated retrospectively by a son who wanted to fix his family's status in stone before his own death.

The chapel at Grangefertagh was built by the MacGillapatrick family, also known as the Kilpatricks, sometime in the fifteenth or early sixteenth century, and the tomb inside it belongs firmly to that world of Gaelic lordship and late medieval piety. The Latin inscription, carved in Black Letter script, names the subjects plainly: John Mac Gilla Patrick and his son Brian, described as former good lords of Ossory, along with Katherine Molloy, Brian's mother. John died in 1468, but Brian, who commissioned the tomb, survived until either 1511 or 1537, meaning the monument was produced sometime before that latter date. It is attributed to the O'Tunney workshop, a school of medieval stone carvers whose output can be traced across Kilkenny and Tipperary and who were responsible for some of the most accomplished funerary sculpture in late medieval Ireland. The sides of the tomb are carved with tracery and vaulting patterns, and the niches along its face contain large foliate quatrefoils, a four-lobed decorative motif common in Gothic stonework, here rendered with considerable ambition.

The tomb sits within the ruined medieval church complex at Grangefertagh, where the carved decoration of the O'Tunney workshop can be examined at close range. The inscription repays attention: the Latin asks for prayers not only for John and Brian but specifically names Brian's wife Nóra and his mother Katherine, layering three generations of commemoration into a single monument.