I am trying to figure out all of the people name dropped by Sir Michael Reresby in episode 6.03. He first mentions his wife and two sons. He then says his wife was a lady in waiting to the Duchess of something that sounds like Cornwall. The only Duchess of Cornwall around that time was Mary, wife of George V before he became king, and only held the title for about 10 months in 1901. It was only used one other time between her and Katherine of Aragon, the first wife of Henry VIII.
Then says "Entertained not just" somebody, again starting with the letter 'C', "but the five princesses". The five princesses are obviously the five daughters of Queen Victoria, Victoria, Alice, Helena, Louise, and Beatrice.
The Duke of Argyll should be the 2nd English Duke, John Douglass Sutherland Campbell, who married Louise. The Queen of Spain should be Victoria Eugenie, granddaughter of Queen Victoria through Beatrice.
Can anyone clarify any of the missing pieces?