Hi Fiona,
There is only one "Salestown" recorded in Griffith's Valuations and that townland is in the Civil parish of Dunboyne, Barony of Dunboyne in County Meath. Counties Dublin and Meath share a common boundary and the village of Dunboyne is only a short distance from the Dublin County boundary.
I have checked for a "Henry" in the townland of Salestown in the Tithe Records - 1823 - 1837 and Griffith's Valuation - c1840 -1854, but did not find any record.
Most "Henry's" appear to be Roman Catholic. There are some Church of Ireland and in Dublin city - Society of Friends - Quaker.
You can access the following records, which are free: Tithe Records: www.nationalarchives.ie/Genealogy, www.askaboutireland.ie - Griffith's.
I attach some detail which may assist in your query. There was a small castle in the area which may be the landmark that Bridget remembered?
Credits: www.findmypast.ie - Meath Heritage.com
Regards,