The tramp of lovers marching through our heroine’s bedroom in the first half of Sonia Purnell’s Kingmaker almost deafens the reader. But then not for nothing did Pamela Digby Churchill Hayward Harriman become known as the alpha courtesan of the 20th century. What is perhaps not so well covered is her decade-long influence on American politics before becoming the United States Ambassador to France under (no, not literally) Bill Clinton.