Agatha Christie tells Frankie that if she ever goes missing she wants Frankie to find her. The real life Agatha Christie went missing for ten days in 1926. She was found in Yorkshire under a pseudonym that included the last name of her husband's mistress. She had no recollection of leaving or what happened over the ten days.
The first shot of the Houses of Parliament shows it is a sandy colour, such as it has been since the early 1980s when it was cleaned of decades of industrial soot. The next shot shows it black, like it was in the 1970s.