Wilson refers to "Fyrmont" as the seat of George Leake in 1786. In 1837 Lewis recorded this house as the seat of W. Sandes. At the time of Griffith's Valuation, the representatives of Lord Hallyburton's estate were leasing this property to William Sandes, whom Bary describes as the most "fair-minded" of the Sandes family and a noted horseman. The house was valued at £13 10s at the time. Prymount was included in the sale of the Gun Mahony estate in 1856 when William Sandes was recorded as the tenant from year to year. It later passed to the Sandes of Swallowglen and was subsequently demolished.