This figure shows up in at least two other Christies, a sort of recurring nightmare: her other appearances are anecdotal, illustrations of what the characters find genuinely creepy compared with more conventional ghost-stories.

I find that so interesting.

Tuppence early on comments that time seems to move at different speeds in some places.

I would love to know if anyone has ever read this novel explicitly from a perspective of folk horror, because that's what the endlessly reflecting motifs and the looping of memory and time remind me of, especially if it's localized to a particular village.