I am a new member so I am not quite sure if this is the proper place to enter the discussion on those two 'cold queens', Swan and Mary.
I know little of the Swan except what I have found out here. However, Mary has always fascinated me. She always seemed to be a repressed figure. I believe that being to some extent on the fringe of the royal families because of her father's morganatic descent which he always felt agrieve by, Mary felt the need for control. She was the most intelligent of her own family and it must have been obvious that she had to make the family's fortune by her marriage. She was, apparently willing to make the sacrifice and marry Clarence to do this. Obviously George was a much better 'deal' for her and they seemed to have a loving relationship. However, he was not her intellectual equal and he was as restrained as she as far as emotions were concerned
and Mary seems to have put all her energy and feelings into her service to the British Crown.
Her statement that she always had to remember that her children's father was also their king, partly explains, I think, her failure to act as a bridge between father and sons. However, I when reading about her, I always feel that she would like to reach out but finds it impossible.