Hi Pughy,
If the family appear on Griffith's Valuations then the Annual Revision Books
should give a guide to the date when the family left Ireland.
Landrum - Griffiths Valuation - Mayo 1856-57
William, Aghadooey Glebe, Burrishoole
William, Carrowkeel, Burrishoole
George, Islands, Inishbiggle, Kilcommon
John, Bleachyard, Burrishoole
Margaret, Doogort, Achill Missionary Settlement, Achill
Alexander, Doogort, West Achill
Alexander, Keel, East Achill
Alex., Sr., Doogort, Achill
Christopher