A graveyard's age is often measured by the stones that survive rather than by those that have been lost, and at Knockboy in County Waterford that distinction matters. When an Irish Tourist Association survey visited in 1943, its inspectors noted that some of the headstones appeared to date back nearly three hundred years, a claim that would have placed the earliest examples well into the seventeenth century. Subsequent examination found no headstones in the graveyard predating 1700, meaning the oldest surviving stones fall just into the eighteenth century rather than before it.

The gap between what the 1943 surveyors believed they were seeing and what the physical evidence actually supports is a small but telling illustration of how easily age accrues in popular memory around old burial grounds. Weathered limestone or sandstone, worn lettering, and the general atmosphere of an ancient ecclesiastical site can all conspire to push perceived dates further back than the carved inscriptions warrant. The graveyard at Knockboy is associated with the ruins of Knockboy church, and while the site clearly has considerable age, the headstones themselves belong to a period when carved grave markers were becoming more common across rural Ireland, rather than to the earlier era the mid-twentieth-century observers imagined.