Factual error: When Chitty Chitty Bang Bang arrives at the Potts' house, Grandpa Potts is sitting in a deckchair reading a very modern colour edition of National Geographic magazine.
Factual error: In the scene where the spies are hanging the false backdrop off the bridge, you can see that the railway lines they cross have concrete sleepers, which is out of period (railway lines at this time would have had wooden sleepers).
Factual error: After they pick up Truly Scrumptious in the newly refurbished Chitty Chitty Bang Bang, look at the road surface as they run alongside the GWR train. There is a broken white line running down the centre of the road. These types of markings weren't introduced in England until the blackouts of WW2.
Factual error: There is a scene where Chitty is pacing the train, which is an 'Austerity' tank engine. This engine was made during WW 2 but the movie takes place in the early 1900s.
Chosen answer: By rules of courtesy titles in the United Kingdom, Truly Scrumptious would inherit no title. Her parents being Lord and Lady Scrumptious, she would be simply Miss Truly Scrumptious. However, if her father were a baron, she would be called "The Honorable Miss Truly Scrumptious." Were her father an earl, duke or marquess, she would THEN be the "Lady Truly Scrumptious." But again, children of a lord and lady do not receive a title. When the lord dies, his oldest son inherits his father's title of lord. If there are no boys, it might pass to the eldest daughter. In this case, only upon her father's death would Truly become "Lady Truly Scrumptious."
Michael Albert