Buchanan won the 1856 election and became the 15th President of the United States. For four years prior, covering the period of the Crimean War, he was the American Minister Plenipotentiary to Britain. His orphaned niece, Harriet Lane, stayed with him in London for much of that time. He had been Secretary of State under James Polk, the American Minister to Russia under Andrew Jackson, and served in both Houses of Congress for eleven years each. Buchanan has been much criticized by historians as a poor President, but he had some admirable personal qualities and showed considerable ability in his other capacities in public office.

In the story... The Duke of Devonshire loves to entertain and often has prominent lunch and dinner guests at his home in London, including Buchanan and his niece. As chatelaine at Devonshire House, Diana is their hostess. She becomes friends with Harriet and on familiar terms with her uncle.