- A family who settled in the Drumsna area of county Leitrim at the beginning of the 18th century. Mr. Simpson of Drumsna was listed as a resident proprietor in Leitrim by McParlan in 1802.Pierce Simpson of Clooncorick served as High Sheriff of Leitrim in 1836. Clooncorick Castle was the seat of the Simpson family during the 19th century although it appears to have been leased from the Ormsby Gore estate. The estate also held several townlands in Mohill parish in the baronies of both Leitrim and Mohill and in the parishes of Elphin and Shankill, barony and county of Roscommon. In the 1870s the Simpson estate amounted to 1,652 acres in county Leitrim, 1,293 acres in county Roscommon and 339 acres in county Wexford. In June 1886 George Simpson, the owner, offered the estate for sale in the Land Judges' Court but the sale was adjourned due to absence of bidding.
- At the beginning of the 18th century William Conolly of Castletown, county Kildare, purchased over 2,000 acres in county Roscommon from the trustees for the sale of forfeited estates. In June 1867 the rental of the estate of Thomas Conolly, Member of Parliament, in the parish of Elphin, barony and county of Roscommon, was advertised for sale. The Irish Times mentions Messers Lyle and Ryan as among the purchasers. At the time of Griffith's Valuation the estate was mainly in the possession of Pierce Simpson. It was comprised of just over 1,000 acres. Some land in King's County (county Offaly) was included in the sale.