The original Strancally castle was built by Raymond le Gros. It was then reputedly occupied by Spaniards, who lured the local landowners to a banquet and then dropped them through a secret trapdoor into a flooded cave. When news of the murder hole leaked out the Spanish were routed and the castle destroyed.
The present building was designed and built around 1830 by James and George Richard Pain for John Keily, MP for Clonmel, and the High Sheriff of County Waterford for 1819–20. It stands in front of the ruin of the original Desmond castle.
In 1856 the castle, in an estate of 5000 acres, was bought by 24-year-old George Whitelocke Lloyd of a wealthy Anglo-Irish manufacturing family. He was appointed High Sheriff of Waterford for 1859–60.  His son William Whitelocke Lloyd was an army officer who fought in the Anglo-Zulu War of 1879 and was an accomplished artist. 
The estate eventually came into the possession of the Irish Land Commission, who sold off the land piecemeal before selling the house with a remaining 160 acres. 
- "Estate: Lloyd (Strancally Castle)". NIU Galway. Retrieved 5 August 2013.
- "KNOCKANORE, GLENDINE, KILWATERMOY HERITAGE SOCIETY". Youghalonline.com. Retrieved 5 August 2013.
- "Ceisteanna—Questions. Oral Answers. - Sale of Strancally (Waterford) Castle and Lands". Dáil Éireann. Retrieved 5 August 2013.