The story of Sarah Blundy incorporates that of Anne Greene,[1] while Jack Prestcott is involved in events based on the life of Richard Willis (of the Sealed Knot).

The accounts are written in the form of memoirs by each narrator many years after the events they describe, after Thomas Ken gained his Bishopric but before the death of Henry Bennet.

A contrast portrayed in the novel is, on one hand, a philosophy based on ancient and medieval learning, and, on the other, the scientific method that was beginning to be applied in physics, chemistry and medicine.

[2] In the original Latin, the term "fingerpost" is simply "cross" (crucis), echoing the decisive "crucifixion" revealed in the story: Francis Bacon, Novum Organum, Book Two, "Aphorisms", Section XXXVI.

[3] A positive review in The Independent described it as a "deeply scholarly thriller", with a narrative that covers themes relating to the nature of truth and knowledge.