William Scott, the Earl of Dalkeith, was the future 6th Duke of Buccleuch. He would become one of the wealthiest landowners in Britain, in possession of Dalkeith Palace, Drumlanrig Castle, and Bowhill House, all in Scotland, and Boughton House in Northamptonshire. His London home would be Montagu House in Whitehall.

In the story... William dances with Diana at the Buckingham Palace ball in May 1856. She hasn't heard from Alan in eight months. William becomes one more future duke in her pool of potential suitors.