Topaz Historical, 1994, ISBN 0-451-40466-1
Siân Jones is the illegitimate daughter of a wealthy English mine owner and a Welsh coalminer's daughter. She was educated in a fine English school. But she turned her back on her English heritage, married a coalminer, and went to work in the mines herself after his death. Now she is engaged to another Welshman, leader of the revolutionary movement of the workers against the tyranny of the English owners. But one of those owners, the Marquess of Craille, has just inherited and come to live in Wales. And he seems sympathetic to his workers. When Siân becomes his daughter's governess, she gets caught very firmly between two worlds--and two loves.