Harriet Lane was the orphaned daughter of a sister of
the 15th President of the United States. He was like a foster father to Harriet. She stayed with her bachelor uncle while he was
the Minister to Britain during the Crimean War. Queen Victoria
her the full status of a diplomat's wife. She served as his hostess at the American legation in London, experience that would
serve her well later as First Lady at the White House.
In the story... Buchanan and Harriet are dinner guests at
in London. As chatelaine, Diana is their
hostess. Prior to the Devonshire House ball, she turns to Harriet to benefit from her greater experience in London society
and they become good friends.