Robert Grierson, A Character In Wandering Willy's Tale In Redgauntlet

In Wandering Willie's tale, by Sir Walter Scott (according to this source), "The Persecutor, Sir Robt. Grierson, is of course the hero of Wandering Willy's Tale in Redgauntlet which Conan Doyle regards as the best short story in the English language."

An excerpt from the story:

A letter in the Darwin Correspondence Project (James Crichton-Browne to Darwin [6 June 1870]) included the following:
My brother Mr. Balfour Browne informs me that the last descendent of the Griersons of Largg (the Redgauntlets of Sir Walter Scott) prides herself on possessing the family peculiarity, the power of producing in a striking manner, the horse-shoe on the forehead.

Grierson (later Greer) is a name I research.