Trading Up, by Candace Bushnell. From a blog post on "Edith Wharton's Influence on Candace Bushnell and Julian Fellowes." http://sarahemsley.com/2013/09/26/trading-up-whartons-influence-on-candace-bushnell-and-julian-fellowes/
Julian Fellowes Overcomes His Scruples and Looks Back at Season 2 of 'Downton Abbey'
Interview with Julian Fellowes, creator of Downton Abbey and of the upcoming ABC Titanic miniseries | "I had always been terribly interested in the story of the Titanic. That doesn’t mark me apart from an enormous number of people."