According to this site, a Duke Ormsby lived in a house called Killeena in County Mayo.
Leased from the Knoxes of Castlereagh by Duke Ormsby at the time of the first Ordnance Survey. Duke Ormsby was closely related to the Rinagry family of Ormsby.
We have since found that this Duke’s descendents continue to farm the same land to this day.
Here’s the map:
According to this site, the first ordnance survey of Ireland was between 1829 and 1842.
The Rinagry Ormsbys are mentioned on the same site here although no details are given:
A small estate in the parish of Kilbelfad, barony of Tirawley, county Mayo, held by a junior branch of the Ormsby family of Gortnaraby. At the time of Griffith’s Valuation they were leasing from the Honourable Edward S. Pery. In 1876 the estate amounted to 553 acres. In the mid 19th century another family member, Duke Ormsby, held two townlands in the parish of Doonfeeny.
But we know the Rinagry Ormsbys descend from Paul Ormsby and Mary o’ Malley, as do the Killeena Dukes as a result of this family tree in the booklet “Pedigree of the Family of Ormsby, formerly of Ormsby in Lincolnshire, now of Ireland. 2nd Series, Vol II, 19” written by J.F. FULLER in 1886.
The reference to Duke Ormsby owning two townlands is mistaken. In fact there were two Duke Ormsbys living in the region at the same time. This one and Duke of Ballinglen.
The Gortnaraby branch seem to have hit hard times during the famine:
By the late 17th century a branch of the Ormsby family had settled at Cloghans, parish of Kilbelfad, barony of Tirawley, Co Mayo and was established at Gortnaraby, parish of Crossmolina, by the mid 18th century. Their estates included land in the parishes of Crossmolina, Kilfian, Doonfeeny and Kilbelfad in the barony of Tirawley and in the parishes of Ballyhean and Drum in the barony of Carra. In 1851 4223 acres of their property was advertised for sale in the Encumbered Estates’ Court, however they appear to have retained their estate in the barony of Tirawley. In 1876 John Ormsby’s estate amounted to 3186 acres, while his uncle the Reverend Horatio Ormsby of Mallow, county Cork, owned 1,114 acres in county Mayo. By March 1916 Colonel John Beecher Ormsby had accepted an offer for the purchase of the estate from the Congested Districts’ Board.
And according to the same site, they were
A branch of the family of Ormsby descended from an Elizabethan settler