Thank you to Amelie who wrote:
Probably not Mrs Anne Hay Mackenzie
"I came across your page in my search for a
painting of Anne Hayes MacKenzie, later Duchess of Sutherland, as I need a
picture of her for a book I want to publish in Hungary.
I surfed for hours and now my conclusion is
that this picture is not of her."
I have found another picture of her. If
I can verify that the source is trustworthy, I should be able to confirm
that the picture above is not of Mrs Anne Hay Mackenzie."
Amelie, Austria: July 25, 2010