The first movie, "Downton Abbey," hinges on a surprise royal visit to Downton. This particular plot point is both accurate and inaccurate in different ways.
Royalty really did (and still does) visit people at their private homes sometimes, particularly members of the aristocracy or those with leadership appointments. "Downton" historical advisor Alastair Bruce explained some of the ins and outs to Town & Country, revealing where the movie hewed close to history and where some creative liberties were taken.
Among the plot points that deviated from reality for the sake of drama: there would be no such thing as a "surprise" royal visit. Royals typically visited their close friends, rather than passing acquaintances (as the Crawleys are described), and with plenty of preparation. Other elements of the movie's royal visit, such as the jam-packed schedule and the massive entourage, are more historically accurate.
