- The O'Conor Don ancestral lands were in County Roscommon centred on Clonalis House near Castlerea. Alexander O'Conor Don died in 1820 without male heirs and the title was inherited by the O'Conors of Bellanagare. Some members of the O'Conor family of Bellanagare were distinguished antiquarians, see the ''Oxford Dictionary of National Biography''. In 1828 O'Conor Don of Belanagar was a member of the Grand Panel of county Roscommon. At the time of Griffith's Valuation, Charles Owen O'Conor was one of the principal lessors in the parishes of Kilcorkey and Kilkeevin, barony of Castlereagh. In the 1870s the O'Conor of Clonalis estate amounted to over 12,000 acres in county Roscommon with another 1000+ acres in county Sligo. At the same time Dennis O'Connor of Kingstown, county Dublin, brother of the O'Conor Don held 751 acres in county Roscommon and 287 in county Meath. In 1879 Charles Owen O'Conor offered for sale lands at Drimina, barony of Lyney, county Sligo. By March 1916 a final offer from the Congested Districts' Board for 1,368 acres belonging to Charles W. O'Conor, nephew of Charles Owen O'Conor Don had been accepted. A similar acreage (1,382) the estate of his mother Ellen I. O'Conor was vested in the Congested Districts' Board on 10 Feb 1916. The estate and family records are still held at Clonalis House. See www.clonalis.com for more information.
- Melvin writes that this was a wealthy branch of the Browne family. Catherine daughter of Martin Browne of Cloonfad, county Roscommon married Denis O'Conor of Bellanagare and they were the parents of the antiquarian Charles O'Conor (1764-1828). Martin Browne's other daughter with a dowry of £2,500 married Thomas Lynch of Lowberry in 1782. By the time of Griffith's Valuation Mrs Margaret Browne retained 66 acres at Cloonfad More and a house valued at £4. The Brownes held Cloonfad from the Mahons of Strokestown. Father Martin Coen indicates that George Joseph Plunkett Browne was a member of this family. He was born in 1795 and was Bishop of Galway and subsequently of Elphin in the 1830s and 1840s .