At the time of Griffith's Valuation Edward B. Thornhill held over 300 acres including the townland of Mount Irvine and a property described as offices, valued at £3. Lewis had recorded Mount Irvine as the seat of William T. Sherlock in 1837. This house is more usually known as Mount Irwin and was a seat of the Irwin family in the eighteenth century. It passed by marriage to the Thompsons and then to William Theophilus Sherlock. It was later sold in the Encumbered Estates Court and the Thornhills continued to own it until 1907 when it was sold to the Land Commission. Nothing remains of the original house.