The castle was supposedly built in 1402 by MacWilliam Mór Synan before being sold to Sir William St Leger in 1630. St Leger demolished the medieval fortress and erected a grand new mansion in its place, impressive enough to catch the attention of Richard Boyle, 1st Earl of Cork, who praised the ‘new mansion house’ during his visit. The house’s fortunes proved less enduring than its reputation; it was burnt during the tumultuous year of 1645, though it was subsequently repaired and surrounded by formal geometric gardens to the southeast, as shown on an estate map from 1728.

By 1750, the once magnificent house had fallen into ruins, standing forlornly in what contemporary writer Smith described as a ‘small grove’. The Ordnance Survey map of 1842 marked only the ‘site of Doneraile Court’, indicating that by then, little remained of St Leger’s ambitious building project. The area saw limited archaeological investigation in 2003, but the most intriguing discovery came in 1990 when a substantial rectangular timber was found approximately 600 metres southeast of the castle site, on the eastern bank of the Awbeg River.

This timber, measuring at least three metres long and 29 centimetres wide, had been hollowed out along most of its length and featured dowel holes on the upper surface of each side, suggesting it once formed part of a larger structure. Dendrochronological analysis dated the wood to 1510, plus or minus nine years, placing it squarely within the period when the castle would have been undergoing modifications or repairs. While we cannot definitively link this timber to the castle, its age and proximity make it a tantalising piece of physical evidence from Doneraile’s long vanished medieval and early modern past.