- The MacDermots were the original hereditary owners of the lands in Coolavin, hence the family title MacDermot of Coolavin. In the 17th century they lost much of their lands but always maintained a presence in the area. In the early 19th century they held a house and demesne at Coolavin. McParlan recorded "Doctor McDermott, son and heir of the late Prince of Coolavin, ........resides in the family mansion". At the time of Griffith's Valuation, Charles McDermott was the lessor of most of the townland of Monasteraden, barony of Coolavin and was also leasing lands in the barony of Tirerill. Portion of this property, including the house and demesne at Coolavin, was offered for sale in the Encumbered Estates Court in 1852. Lands in the barony of Tirerrill were offered for sale in March 1860. In the 1870s Charles J. McDermott owned almost 800 acres in county Sligo while Roderick and Thomas McDermott owned another 800.
- This estate was centred around the house at Alderford, near Ballyfarnon, in County Roscommon. It included some land in the parish of Tuam, barony of Dunmore, county Galway in the mid 1850s. MacDermott lands in the parish of Kiltrustan, barony and county of Roscommon were offered for sale in January 1852. The MacDermottroe family were connected with the MacDermot family of Coolavin. In the 1870s Thomas Charles McDermott owned 2,505 acres in county Roscommon. See http://www.macdermot.com/library/Origins.html for further details.