First recorded in 1570, the castle belonged to the MacClancy family, who served as hereditary brehons (legal scholars) to the powerful O’Briens of Thomond. Their fortunes changed dramatically after the Irish Rebellion of 1641, when their ancestral home was confiscated and handed to Patrick Sarsfield. The property then passed to the Purdon family before the tumultuous Cromwellian invasion of 1649 to 1653 saw it change hands multiple times. By 1752, the William McNamaras were renting the castle, though it appears to have fallen into ruin sometime before 1787.

Today, no visible remains of the castle survive above ground, but tantalising clues emerged in the 1980s. When the farmhouse owner demolished a particularly wide southern gable wall around 1980, he discovered architectural features that told a different story. Built into the wall were two narrow loops in splayed embrasures; classic defensive features of a medieval castle. The salvaged stonework, later examined by historians Risteárd Ua Cróinín and Martin Breen in 1997, revealed typical fifteenth-century dressed masonry, including three rounded corbels and the base of a late sixteenth-century square-mullioned window complete with holes for glazing bars. These stones now form part of the farmyard entrance immediately to the south.

Local folklore adds another layer to the site’s significance, with residents pointing to a high mound across the road as the possible location of the MacClancy law school. As hereditary brehons, the MacClancys would have maintained such a school to train future generations in Brehon law, the ancient Irish legal system that governed Gaelic society for centuries. While the castle itself has vanished, these fragments of worked stone and persistent local memories ensure that Knockfin’s story endures in the Clare landscape.