William and Mary Rowan (or Ruane) ORMSBY born in Sligo, to Liverpool, before the 1841 Census

Hello, 

I'm researching my Irish ancestors, William (c.1790-1859) and Mary Rowan Ormsby (c.1795-c.1845) who were born in County Sligo, but by the 1841 Census they were in Liverpool, Merseyside, with their known children all born in Ireland between 1823 and 1839: Ann, Margaret, Mariah, John, Thomas, Catherine, William Jr., and possibly a daughter Sarah. 

On a census record and then on his daughter Margaret's marriage license, William Sr. lists his occupation as Shipwright and Ship's Carpenter. I think he died in 1859 in Liverpool. 

Based on census records in Liverpool, I think William's wife, Mary, probably had at least two sisters, Ellen and Margaret. Margaret's husband was Henry Murphy.

I'd love to find William and Mary Rowan Ormsby's town in Sligo. I have speculated that a shipwright or ship's carpenter would probably live where there were ships, so I think I should look around Sligo Harbor. I doubt I'll find birth or baptismal records, however, maybe there's a listing for William in a Sligo directory or a clue as to his parish. 

Thank you. Any advice would be most welcome.

Wishing you a pleasant day,

Jan Mulligan