The church itself dates to 1709, a relatively modest piece of ecclesiastical history, but tucked into the south-west corner of the chancel is a baptismal font that predates the structure by centuries, the sole surviving remnant of whatever medieval foundation once occupied this ground.

The font is plain and octagonal, set on its original plinth, measuring 0.68 metres in diameter and standing 1.1 metres tall. A baptismal font, for those unfamiliar with the term, is the stone basin used to hold water for the Christian rite of baptism, and in Irish parish churches they were often among the most durable furnishings, sometimes surviving the collapse or replacement of entire buildings around them. That appears to be exactly what happened here. When the current church was constructed in the early eighteenth century, the medieval community it replaced left almost nothing behind, and yet this font endured, repositioned into a corner of the new chancel where it has remained ever since. The antiquarian Adams noted it in 1881, by which point it had already been standing for an unknown number of centuries.

Santry is now largely absorbed into the northern suburbs of Dublin, and St. Pappan's sits within that suburban fabric rather than in open countryside. The church is a Church of Ireland building and access to the interior would typically require arrangement in advance or attendance during services. The font itself is unadorned and easy to overlook if you do not know to look for it, a small, grey, eight-sided column in a corner, carrying no inscription and making no claims on the attention. Its interest lies entirely in what it represents: an object that survived a complete institutional rupture, standing in a building that does not share its history.