It's my site that Lorraine has been suggesting. I'm not sure that it will help much, but you might want to look over the Leader portion.
Yes, "Leader" is a lousy search term in Google. The name itself means military leader and is of English origin. The Leaders of County Cork were, supposedly, descended from a "Cromwell soldier" and were landed gentry, primarily in the Millstreet (a town in northwest County Cork) area and were part of the Anglo-Irish ascendancy. I am also reasonably certain that there were members of the family who did not remain part of the ascendancy. My own Leader ancestor, though from Millstreet, seems to have been both poor and Catholic.
"Queenstown" is now known as Cobh and is in Cork harbor. I didn't know that there were Leaders there, but I'm not surprized.