The surrounding Rathaspick parish witnessed a gradual shift in power during the medieval period, with the Codd family holding sway in the 14th and 15th centuries whilst the Esmonds maintained only a modest foothold. By the 17th century, however, the tables had turned; William Esmond had amassed considerable holdings including 185 acres at Johnstown, 94 acres at Whitestown and 57 acres at Scaughmolin by 1641, leaving Nicholas Codd with just 80 acres between Rathaspick and Ballykelly. The turbulent Cromwellian period saw William Esmond marked for transportation in 1653, and his lands subsequently granted to Colonel John Overstreet, governor of nearby Duncannon fort.

The estate’s ownership continued to shift through marriage and inheritance, passing from Overstreet’s widow to Edmund Withers around 1668, then to Colonel John Reynolds, whose daughter Mary’s marriage to John Grogan, a merchant from Wexford town, established the family that would shape the castle’s most dramatic transformation. The Grogans retained the estate well into the 19th century, with Hamilton Knox Grogan Morgan orchestrating the castle’s remarkable neo-Gothic makeover before his death in 1854. This reimagining incorporated elements of earlier structures, including portions of a 17th century building believed to survive in the northeast front, whilst a 16th century tower house attributed to the early period was eventually demolished around 1945.

Today, the castle serves an entirely different purpose from its defensive origins. Handed over to the Irish State in 1948, it became an Agricultural Institute and remains under the stewardship of Teagasc, Ireland’s agriculture and food development authority. The castle sits elegantly on a gentle rise overlooking an artificial lake that stretches 400 metres north to south, its waters likely dating back to at least 1839 when they first appeared on Ordnance Survey maps. Visitors can explore both the meticulously maintained gardens and the Irish Agricultural Museum, housed in the farm buildings just 100 metres east of the castle, where centuries of agricultural heritage complement the site’s rich political and architectural history.