The founder of the Irish branch of the Gosford family was Archibald, eldest son of Capt. Patrick Acheson, a cadet of the family of Acheson of Gosford, East Lothian, and Acheson House, The Canongate, Edinburgh. He was born in Edinburgh, but settled in Ireland, near Markethill, as early as 1610. The family estate extended from here and by 1817 amounted to approx. 8000 acres in the Co. Armagh area, rising to 12,000 by the late 1820s with additional lands (approx. 6500 acres) in Co. Cavan. The Family seat (which Jonathan Swift visited and whose occupants he satirised in verse) was burned down in 1805 and a splendid neo-Norman castle (Gosford Castle), the largest house in Ireland, was built 1819-c.1862 by the 2nd Earl. The 3rd Earl was a bibliophile who collected a vast library which was sold by his son the 4th Earl in 1878 to settle a gambling debt. The remaining contents were sold in 1921 when the family left; the house lay empty until it was requisitioned during World War II; subsequently variously used, and latterly in the hands of the Forestry Commission, proposals from a number of potential purchasers are being considered in May 2002. Since 1958 the demesne has been administered by the Forestry Commission as Gosford Forest Park.