This fortification is believed to have been constructed by a junior branch of the Roches of Artramon, though Walter Roche of Newcastle remains the only documented proprietor. The Civil Survey of 1654 to 1656 records that Walter owned what was described as "a handsome castle in indifferent repair", suggesting the structure was already showing its age by the mid-17th century.

Walter Roche's holdings were substantial for the time; in 1640, he possessed 960 acres across Tikillin parish, encompassing the townlands of Newcastle, Killowen, Ballytarfan (also known as Ballyharran), and the now-lost Ballyboggan. He also controlled the strategically important ferry crossing at Ferrycarrig. The castle's decline was gradual but inexorable; by the time Taylor and Skinner produced their map in 1778, Newcastle was already depicted as a ruin, and both the 1839 and 1941 Ordnance Survey maps mark it simply as the site of a former castle.

Today, visitors to Newcastle Upper will find no visible remains of the structure that once dominated this corner of Wexford. The Down Survey parish maps from 1656 to 1658, held in the National Library of Ireland, provide one of the few visual records of the castle's location, marking a spot that has since been absorbed into the rhythms of agricultural life. The transformation from defensive stronghold to farmland tells a familiar story of Ireland's changing landscape, where medieval fortifications have given way to the practical demands of modern farming.