Richard, Robert and John Irwin were occupiers and lessors of property in the parish of Baslick, barony of Castlereagh, county Roscommon, at the time of Griffith's Valuation. John Irwin, a younger son of Richard Irwin of Rathmoyle, was residing at Raheen in the parish of Elphin, barony of Roscommon. In the 1870s John Irwin of Raheen owned 248 acres in county Roscommon and 1,527 acres in county Sligo. His brother Richard of Rathmoyle owned 3,628 acres and their cousin Robert Irwin of Emla owned 933 acres in county Roscommon. At the time of the first Ordnance Survey Richard Irwin of Dublin held two townlands in the parish of Turlough, barony of Carra, county Mayo. John Henry Taaffe leased one townland and Perkins of Ballina was agent for the other. Rathmoyle was sold in 1921 and this branch of the Irwin family resided after that in England.
Over 300 acres of the estate of John, Lynden and William Irwin at Tullaghan, barony of Frenchpark, were offered for sale in the Landed Estates' Court in May 1868. This comprised the entire townland which had been in the possession of Caleb Robinson at the time of Griffith's Valuation. It was sold to John Hatchell Triston, in trust.