Ah, so this is actually a record from c1910, when she would be approximately 70? But it doesn't give her age in 1851, so I'm still not sure I have the right person, or her daughter or mother, all of whom had the same name. The address given is in Belfast, but the homeowner's name is not that of anyone in her family living or staying there at the time. What few records I've found of births and deaths have all been in Antrim, but in various villages such as Ballymore. (I'd have to go back to my tree in Ancestry for the names of other villages and towns in what records I've found so far.)
Thanks for the suggestions! I obviously have to get my mind out of the groove worn by years of looking at Scottish and Canadian records. The search format becomes automatic after that length of time.
Now, after typing this reply so far, I find more have come in. The Achesons did live in Armagh at one point, so that would be the same Ellen. I guess. Oh, dear. This is like a family I found in my own Scottish ancestors where three brothers had their first sons all born in the same year, and, as was the traditional naming pattern, all three little cousins were named after their fathers' father, and I didn't know which one was my ancestor.
I was searching using Ancestry.com. Thanks for the link to Home. I'll have to do some self-education before I take this Irish research any further, obviously! A job for this evening after I get home from work, so if i don't reply immediately to other suggestions, I will later in the day.