This is probably a long shot Mercel but who knows? Michael Devlin, son of John and Ellen Devlin came to Greenock in the 1870's from Coal island in co. Tyrone. Ireland. As far as I know his two brothers, Patrick and John stayed on to work on their father John's farm. John would have been been born in the 1830's. Your ancestor Patrick just might have been related, maybe even a brother!
I take it Daddy Patrick Devlin and Mary Ann returned to Durham?
Happy searching
Rosie