This surname is thought to be a personal name said to be
an offshoot of the Highland family of MacGregor. This name is of Scottish
descent and is found in many ancient manuscripts in the above country.
Examples of such are a Gilbert Griersoun who had a grant in 1411 of
Mekildaltoun and Dormont from Archibald, Earl of Douglas. William Grerson
had a safe conduct into England in the year 1451. Names were recorded in
these ancient documents to make it easier for their overlords to collect
taxes and to keep records of the population at any given time. When the
overlords acquired lands by either force or gifts from their rulers, they
created charters of ownership for themselves and their vassals. Other
examples of this name were found in the person of Robert Greresoune in
Dumfries who had a remission for the slaughter of Sir John Mc Brae,
chaplain, in 1502 and Sir Robert Grierson of Lag was notorious for his
severity and bloodthirstiness to the peasantry of Galloway.