This is filmed in Eastnor Castle, Ledbury, Herefordshire, UK. Where the 1986 version with John Gielgud was also filmed.
During the race in the first In the episode, Ginny can be seen riding high, obviously standing on stirrups even though she is supposed to be riding bare back. The saddle must have been deleted in post-production.
In episode 1.2 (Summer), there is a long shot of the church while the minister is praising the joys of the new church roof, but the roof does not look new. It has numerous patches of green moss and what looks like at least one repair.
Harry Gostelow (Lord Canterville) and Carolyn Pickles (Mrs. Umney) are first cousins in real life. His mother, actress Vivian Pickles, and her father, Judge James Pickles are brother and sister. Their other sister is actress, Christina Pickles; best known as Ross and Monica's mother on Friends.