On 11 June 1707 Sir Arthur Shaen leased the lands of Lenarevagh, parish of Kilcommon, barony of Erris, county Mayo, to John Irwin. In 1852 George and John Irwin advertised for sale an undivided moiety of their lands. In 1876 William and Thomas Irwin each owned 555 acres in county Mayo.
National Archives of Ireland:
Encumbered Estates' Court Rentals (O'Brien), Irwin, 29 June & 30 Nov 1852, Vols 16 & 19, MRGS 39/007 & 39/009, (microfilm copy in NUIG)