Theophilus Sandford was the first member of the Sandford family to obtain extensive lands in Castlerea. As a member of Cromwell’s army in Ireland, he received a large allocation of lands confiscated from the O’Connor Don family, which included Castlerea. The grant was part of the Act for the Settlement of Ireland 1652, which was revised in 1662 after the restoration of Charles II.
Castlerea developed under the Sandfords, who established a distillery (at its height producing more than 20,000 of gallons of whiskey annually), a brewery, and a tannery. His descendants continued in power through the 19th century. The estate was acquired by the Land Commission and the Congested Districts Board. The demesne in which it was set survives; the people of Castlerea now enjoy it as a public park.