- Patrick Grehan had a lease of the Mountplunkett estate, parish of Killinvoy, barony of Athlone, county Roscommon, from 1847 and appears to have bought Crotty's interest in the property in 1851. In the 1850s Patrick Grehan held lands in the parishes of Killinvoy and St Johns, barony of Athlone, county Roscommon. In January 1870 the estate of Patrick Grehan amounting to 2,745 acres in the baronies of Athlone, Ballintober, Ballymoe and Castlerea was advertised for sale. The Mountplunkett estate and the part of South Park Demesne in the barony of Castlereagh were readvertised in May 1870. The Irish Times reported that these lots were sold to Rev. W. West and Owen O'Connor.
Crown Life Insurance Company
- The Crown Life Insurance Company of 46 and 47 Dame St, Dublin, owned 769 acres in county Roscommon in the 1870s. This company held the townland of Rinnagan, parish of St Johns, barony of Athlone, formerly part of the estate of Patrick Grehan.