The setting for this popular series is Highclere Castle where Lord and Lady Carnarvon reside. Julian Fellows seems to have used some of the family's history for plot lines in his series. Highclere Castle itself has had many colorful occupants which were revealed by Lady Fiona Carnarvon in an interview about the castle. The 5th Earl of Carnarvon funded architectural digs in Egypt which resulted in the discovery of Tutankhamen's Tomb and Lady Almina may have been the inspiration behind Elizabeth McGovern's character, The Countess of Grantham. She used the house as a convalescent home for officers returning home injured during WWI. Lady Carnarvon in a PBS program about the castle showed the bedroom that was converted to an operating room during that time.
In Parade Magazine's article, Julian Fellowes also talks about his own family history and how it shaped his screenwriting for Downton Abbey. He says Violet Grantham was based on his tyrannical great aunt, Isie. Robert Grantham is drawn from memories of his father who was a deeply moral man, but he is quick to point out was cleverer than Robert Grantham. His mother, although from a respectable middle class family, was of a lower birth than his father, something his father's side of the family disapproved of even though (as Julian's brother often states) their father was part of the "landless gentry".
Julian Fellowes friendship with Lord and Lady Carnarvon and his own upbringing give him a unique insight into the upstairs/downstairs characters of Downton Abbey. He gives each of the characters their own story and whether upstairs or below, he makes each of the characters significant.
Watch Secrets of Highclere Castle on PBS. See more from Secrets of the Manor House.