La Dame Blanche means 'the White Lady', a mythical figure from European medieval folklore known in various myths to be witches, healers, sorceresses, spirits or ghosts. Some myths portray them as kind and helpful, while others portray them as evil and harbingers of death. They are also seen to punish those who treat them badly.
Claire finds out about the affair between her friend and Bonnie Prince Charlie because he was bitten by her monkey. In real life the first cousin of England's Prince Phillip who was King of Greece died from a monkey bite in 1917.
Pope Benedict XIV was Pope from 1740 to 1758. He is the Benedict Jamie mentions that the Duke wanted to meet.
At the dinner party, Louise attempts to change the subject away from politics and suggests the opera. Simon Callow (The Duke of Sandringham) previously starred in The Phantom of the Opera (2004) as Andre, one of the new owners of The Paris Opera House.