The earthwork appeared on early Ordnance Survey maps from the 19th century; first shown as a hachured enclosure suggesting either a ringfort or barrow, then later depicted as a hachured mound and annotated simply as ‘Moat’ on the 1908 survey. This change in how it was recorded hints that surveyors recognised it as something more substantial, possibly the remains of a Norman motte castle. By 1994, when archaeologists went to inspect the site, St Mary’s Church of Ireland had been built there and no visible traces of the earthwork remained above ground.

The manor itself has a fascinating history of conflict and royal connections. In 1290, when Henry Compton received a grant for the demesne lands of the royal manor of Crumlin, he met fierce resistance from local tenants who had previously held the farm of the manor. Documents from 1331 describe nearby Saggart as an ‘ancient ferm’, whilst a decade later both Crumlin and Newcastle Lyons were recorded as being ‘of the king’s ancient demesne’. According to historian A. Foley, this classification as ancient demesne might indicate these manors were originally part of Norse demesne lands, suggesting a continuity of administrative importance from Viking times through to the medieval period.

The possible motte at Crumlin represents the kind of fortification that Norman lords often built to control newly acquired territories in Ireland. These artificial mounds, topped with wooden palisades or towers, served as both defensive structures and symbols of authority. The proximity to St Mary’s Church is typical; medieval lords often positioned their strongholds near religious sites, creating administrative and spiritual centres that reinforced their control over the surrounding lands and people.