Oldcourt takes its name from a building that had already vanished before anyone thought to map it carefully, and by the time the Ordnance Survey visited in 1839 to 1840, the cartographers could only mark a dashed circle, roughly 25 metres across, to indicate the general area where something once stood. A dashed line on an Ordnance map is a particular kind of symbol, reserved for features that are suspected or inferred rather than seen; this one has served as the site's only formal marker for nearly two centuries.

What stood here, tradition insists, was a court, in the older sense of a substantial enclosed residence or fortified dwelling. Writing in 1905, the historian William Carrigan recorded that the place lay within a few perches of the hill-road between Inistioge and New Ross, and that only the grey enclosing walls still remained at that time. He also preserved the oral tradition attached to it: the building was said to have been the residence of Griffin McCroo, described as the brother of Ross McCroo, the woman credited in local memory with founding the town of New Ross across the county border in Wexford. That connection, if it ever had a firm historical basis, has not survived in any documentary form, but the name McCroo and the founding of New Ross belong to a period of medieval settlement and town-building that reshaped this part of the Barrow and Nore valleys. Whether the tradition reflects genuine memory of an early medieval household, a later medieval enclosure, or something else entirely, there is now no way to say with confidence.

Today the building is not visible at ground level. The slope above the Nore holds the site, but the walls Carrigan described have since disappeared from view, leaving a place that exists mainly as a name, a dashed line, and a fragment of local tradition about two siblings and the town one of them may have founded.