Penmarric by Susan Howatch

 I've just been re reading Penmarric which was a big hit back when it was published in the 1970s... it was a best seller which had a solid historical background.

I think that Howatch was the first writer to use a historical story as a skeleton for her own story.  She has based her novel on the history of the Plantagenet kings, particularly King John.. and set it in 19th and 20th C Cornwall. The novel starts in 1890 with the narration being done by Mark Castallack, a young upper class man who is based on Henry II.  He falls in love with a working class widow, Janna Roslyn, (Eleanor of Aquitaine) who is left badly off by her elderly husband, a farmer.. and is being persecuted by her 2 step sons. 

The couple fall in love and Mark marries her.  She is in love with him but the marriage is not a success.  Janna is 11 years older than her husband, and while he is at first drawn to her by her beauty  and her passionate nature, he grows bored with her because of their class differences and her lack of education.  He begins to spend time visiting Oxford and writing historical works, while Janna produces a large family of children.  Mark finds a large family tiresome and resents the way that Janna tends to use the children to avoid socialising with the upper classes in their neighbourhood. 

Janna's favourite child is Philip, her third son, who shares her love of Cornwall and who is very interested in the mine on the estate.  When he is 10, he and Janna go during half term holiday to Brighton, because Philip wants to move to a school in that area.  Mark is not home and Janna thinks he is in Oxford, as he mostly is.  When they go to dine at their hotel, to her horror, she sees Mark with a younger woman and 2 young boys.  She has known for some time that Mark had a mistress, a former governess called Rose Parrish, but she did not realise that they were in contact all the time..   A row breaks out.  Janna realises that Mark is living with Rose, who is acting as his housekeeper and that he is now at a point where he wants to end the marriage.  

She and Mark leave Philip alone and go to talk.. Mark telling her that the marriage is over and he wants  a divorce.  Angrily, she refuses not wanting to let him become free to marry Rose.  In his anger, he forces her to have sex with him.