Grantstown, Queens Co is attributed by Carrigan to Sir William Grant the Elder's family. He points out that Rathlogan, quit claimed by Sir William's grandson, also William, in 1305, was nearby in Glashloe Parish, Galmoy Barony. And that also William witnessed a document of John Piper in Rathdowny (also nearby) in 1290. The Macgillapatricks, who had previously controlled the land in North Ossory fought a long and biter war against the Norman invaders, and eventually expelled them in the middle of the 14th century. Perhaps the name of the townland is all that is left of the early Grants in the area.

Grantstown, Tipperary S.R, is attributed to a family of le Grant of the 13th century by Flynn in the Book of Galtees. He records that there were a number of references in the Calender of Justiciary Rolls between 1295 and 1313. Then there is no mention of Grants in the area until the 19th century. Again it would seem probable that the Grants entered the area with the early Norman conquest, then had to withdraw because they were on the borders of the Norman colony and subject to border raids.

Grantstown, Co Waterford, comes from an area close to Waterford that is not covered in the history of the rights and fees of the early colonists. but again we know from the records that do exist that Sir William le Grant's brother John was murdered in 1313 by Robert le Mineter and a gang of Irish felons at his home which was nearby at Ballyglan. If the Grants ever owned this area, it must have been prior to 1450.