The actress Mary Ellis was 96 at the time of filming.
Mary Maberley (played by Mary Ellis ) reports to Dr. Watson that her son and daughter-in-law died in a climbing accident. In 1950, Ellis' own husband also died in a climbing accident.
At the costume revels, a boat with a woman lying in it drives by. It is a reenactment of Sir John Everett Millais's famous oil painting "Ophelia" (1851-1852).
Emma Hardwicke, who played Dora, is the daughter of Edward Hardwicke who, of course, played Dr Watson.