Who is Tom Ringer from This House of Sky: Landscapes of a Western Mind and what is their importance?

Tom Ringer was Ivan Doig's maternal grandfather. His role and reputation in the memoir are a bit peculiar. He is reported to have been considered rather a 'never-do-well' type of fellow, and perhaps a little notorious as a drinker. He was encouraged to, or allowed to marry the daughter of a man near to his own age- the daughter of one of his peers.