From the information I have, James Kirk is the youngest son of Rev. John Kirk (1795 - 1858). I found his death mentioned in a paper which I have transcribed as follows:
At Kelly, near King Williamstown, Cape Colony, on 2nd October, James Kirk, in his 58th year, youngest son of the late Rev. John Kirk, of Arbirlot.
I am hoping to find his death record or any other clues.