She wrote over 100 historical romances, the first published when she was 44, many based on the industrial society of northern England in the nineteenth century, where young women from poor backgrounds made a success of themselves. Her total sales by the time of her death were over 100,000,000 volumes and she was consistently among the 10 most heavily-borrowed authors from British public libraries; a survey in 1988 showed that every third adult fiction book borrowed was by her. She married but never had children.