- Some of the O'Donnells of Ulster settled in county Mayo in the 17th century, initially in the Ballycroy area. From there they branched out into Achill and by the 1760s were in the Newport area. They are believed to have been heavily involved in the smuggling trade and by 1781 were prosperous enough to purchase the estate belonging to the old Abbey of Cong on the Mayo/Galway border. In 1785 they bought the lease of the Manor of Burrishoole from the Medlycotts, which established them as the main landowners in the barony of Burrishoole, county Mayo. Patrick Knight, writing in 1836, stated that they also owned 30,000 acres in the barony of Erris. By 1850 the O'Donels were in severe financial difficulties. Much of the Achill part of their estate was bought by the Trustees for the Achill Mission in the early 1850s and the Cong estate was sold to Joseph Lambert and Manus Prendergast, trustees to Alexander C. Lambert. The sale of the different lots of the O'Donel estate is summarized in Appendix 2 of Peter Mullowney's thesis. In 1876 Sir Richard A. O'Donel of Newport and his son George still held over 7,500 acres in county Mayo. In 1911 Melicent Agnes Thomas O'Donel sold the remainder of the O'Donel estate to the Congested Districts' Board at the suit of the Scottish Amicable Life Assurance Society to whom it had been mortgaged.
- From 1722, George McNamara held the Abbey lands in the parish of Cong, barony of Kilmaine, county Mayo and associated land from the Tasburgh family. George McNamara was involved in litigation over the ownership of the Abbey lands in the 1730s. By the 1770s at least 500 acres, including the Abbey and the lands of Cornamona and Clogher, county Galway, formerly held by George McNamara (died 1760), were being leased by his brother-in-law, Stephen Creagh Butler, to his son, Bartholomew McNamara. The Irish Tourist Association file records that Bishop Pococke described the Abbey House in 1770 as the most delightfully situated residence he had seen in the course of his travels. In 1786, Wilson refers to "the beautiful seat" of George McNamara. The Abbey lands were acquired by Sir Richard O'Donel of Newport in the 1780s and sold to Joseph Lambert of Brookhill, parish of Crossboyne, barony of Clanmorris, in 1852.
- The Lamberts of county Mayo were descended from the county Galway family located at Cregclare and Aggard. From the early 18th century the county Mayo branch were leasing land in the barony of Kilmaine from such families as the Veseys, Ruttledges and Bowens. They lived at Togher and Rusheen or Thomastown but moved in the late 18th century to reside at Brookhill, parish of Crossboyne, barony of Clanmorris, leased from the Gonne Bells. They were closely linked to the Ruttledge family, Joseph Lambert of Brookhill having married in 1784 Barbara Ruttledge sister and heiress of Robert Ruttledge of Bloomfield. Their second son the Reverend Francis Lambert changed his name to Ruttledge and continued the family of that name at Bloomfield. Joseph Lambert married secondly Mary Clendining and their sons Joseph and Alexander C. were agents to many of the landowners in the locality. Alexander Clendining Lambert bought almost 1000 acres of the O'Donel of Newport estate in the Cong area in 1852 and sold it to Benjamin Lee Guinness in 1858. In 1854 he bought much of the land he was already leasing from the Brownes of Castlemagarret in the Encumbered Estates' Court and other property in 1860 from the sale of the Brownes of Claremount estate. In 1876 Alexander C. Lambert owned 1409 acres in county Mayo and 1121 acres in county Galway. His property in the barony of Ballynahinch was purchased from the Thomson family of Salruck. The Brookhill estate was gradually sold in the 1920s and 1930s and the house and about 100 acres in 1946 to Gerald Maguire, a solicitor in Claremorris. In the mid 20th century Alexander Fane Lambert, wrote a detailed account of the history of his family and its land holding, based on family papers still in the possession of a family member in London.
- The Salrock/Salruck estate, barony of Ballynahinch, county Galway, originally belonged to the Miller family of Milford, parish of Kilmainemore, county Mayo. In 1803 it was estimated to contain approximately 8000 statute acres stretching along the western coastline from the Killary Harbour to Cleggan. In 1815 Colonel Alexander Thomson married the widow of General Charles Miller who was killed in the Peninsular War. Colonel Thomson had some claim on the Milford estate and after a protracted law suit he purchased in lieu of this claim the Salruck property in the early 1830s. Members of his family continued to follow military careers and one of them was agent to Mitchell Henry at Kylemore Abbey. In 1876 the Thomsons still owned an estate of over 8000 acres in county Galway. 1332 acres of their estate was sold to the Congested Districts' Board on 2 Apr 1897 and by March 1916 a final offer for a further 7,819 acres had been accepted by the family. Alexander Thomson leased 13 acres of Illaunroe to Sir William Wilde in 1853 and the farm of Dernasliggan, 250 acres on the edge of the Killary, to Alexander C. Lambert in 1854. Descendants of the family still live at Salruck House and own some land in the locality.