The 1806 building that stands today replaced something considerably older, and the older building itself was already a remnant of a monastic connection that once stretched from a Dublin village to the English county of Worcestershire.

According to Francis Elrington Ball's 1920 history of County Dublin, the church on this site was attached to the Benedictine Priory of Little Malvern, a house of that order located in the Malvern Hills of England. The Benedictines, a monastic order following the Rule of St Benedict, held properties across medieval Ireland as well as Britain, and a dependent church in a Dublin village would not have been unusual for a priory of that standing. Before the current 1806 structure was raised, the earlier church was recorded in an illustration by a Reverend Wynne, referenced by O'Driscoll in 1977, which shows a simple nave and chancel arrangement with a belfry tower. That image is now among the few traces of what preceded the Georgian rebuild. At ground level, nothing of the medieval fabric survives to be seen.

The church sits in Castleknock village, a western suburb of Dublin that has retained something of a village character despite considerable development around it. St. Brigid's is a working Church of Ireland parish church, so access to the building itself depends on service times or arranged visits rather than open-door wandering. The site is not one where you will find excavated remains or interpretive panels pointing to the buried history; the interest lies precisely in knowing what is not visible. Anyone familiar with reading Wynne's 18th-century illustration before arriving will find the contrast between that recorded image and the present building quietly instructive about how thoroughly a site can be rebuilt and the earlier layers absorbed without trace.