Ruskie,
I emailed the person I'm helping, she's not confident. For a start she doesn't know where there was money in her pedigree to pay an artist for their skill.
The picture was in a collection of her mother's papers, but in isolation. She's working on some thoughts.
By posting here to get an opinion of the date of the portrait and the age of the man she hopes she can identify him by elimination. I hope to visit her in a few weeks and have two heads gong on the conundrum, mine with no preconceptions. Sometimes other people's brisk walls are more interesting than your own, and it keeps your skills honed.
Thank you for your efforts, I'll post on here if we think we have him identified.
Happy hunting
Canuc