In the closing years of the seventeenth century, a Rent Roll belonging to the Duke of Ormond recorded it without ceremony: a stone house by the Green, out of repair, with a garden attached, occupied by the Rev. Pierce Purcell, P.P., and used as a Mass-house. It was a matter-of-fact entry in a landlord's document, yet it marks the earliest known evidence of organised Catholic worship in Callan after the Reformation, a period during which such buildings occupied a legal grey area at best and a dangerous one at worst. The same building, or one closely related to it on the same plot, was still in use as late as 1704.

The history of the site becomes slightly more complicated from there. By 1816, when the Rev. Michael Forrestall became parish priest, the building in use was probably not the original stone house but a later chapel that had replaced it on the same ground. Forrestall secured a lease on this structure and promptly set about replacing it with something more permanent. The construction required demolishing the west end of the existing chapel to make room for the new one, meaning the two buildings briefly overlapped in space if not in time. The present church sits partly on the footprint of that earlier structure, somewhere on the western side of Green Street, a little to the east of where it now stands.