I know it's a long time since you all posted this thread but I've just come across it.
My husband's grandmother was Mary Anne Cawley, born 1889?, she left Belmullet for England in the early 1900s and ended up in Newcastle-upon-Tyne. From her marriage certificate in 1914 her father was Patrick, a farmer. I think I have found the family in the 1901 and 1911 census records
1901 - Tallagh, Kilmore, Erris, Mayo Cauley, Patrick, age 40 a farmer Mary wife, age 40 Micheal, age 15 Patrick, age 14 Mary Anne, age 12 Kate, age 10
1911 - Tallagh,Belmullet Patrick, Roman Catholic, age 66, farmer Mary, age 68, married 34 years, had 6 children, 4 surviving Patrick, 25, labour Kate, 23 - the only one of them to be able to read and write They all spoke Irish & English
The family believed that Mary lived on an island, now uninhabited, off the west coast of Ireland, but they must have moved to the mainland when she was a child if so.
Grateful to hear if this family fits in with any of yours. Andrea