Photographer: unknown
Location: unknown (most likely Berwickshire, Orkney, Edinburgh or Glasgow)
Subject: "Mrs Walker"
An estimate of the date the photograph was taken, and your best guess at the age of the female subject, please.
This may be the mother-in-law of Agnes Frisken (1821-1898). Agnes was the younger sister of George Frisken from [1]. Agnes married William Walker, a Mason's apprentice. William's mother was Catherine, born in about 1791. Would her age seem to fit this photo? Or would this be Agnes "Walker" after her marriage?