What is the theme in The Children of Men by P. D. James?

Power iscertainly a large theme in this book. The novel displays a constant struggle for power. The rivalry between Theo and Xan is initiated by a rivalry between their mothers. Mrs. Faron was jealous of her sister, who married a Baronet and lived in a mansion. This tainted Theo's perspective, and when he first visited Woolcombe he believed Xan would make him stay in the servant's quarters.