The facility is run by Doctor Algernon Chettle, a phrenologist who believes that the shape of a person's skull determines their mental stability.

[2] Littlewood found researching the treatment of mental illness in Victorian times "disturbing", in particular the processes used to certify a person insane.

"[2] Littlewood stated that Nathaniel is an unreliable narrator because the story is told from his narrow perspective, which includes his perception of Mrs Harleston.

[2] Reviewing the book in the British science fiction magazine, Starburst, Alister Davison described The Crow Garden as "a sublime blend of the psychological and the supernatural" that is "eerie and unsettling".

[3] In a review for the Historical Novel Society, Douglas Kemp wrote that The Crow Garden "is a well-written and entertaining story" that explores "the murk of mental illness" and its treatments in 19th-century England.

[4] He described Kerner as "the epitome of the unreliable narrator", making it difficult for the reader to know what to believe, and said his obsessions with Mrs Harleston leads to a madness of his own.

[5] She said the ending is open-ended and Littlewood leaves it up to the reader to decide what to make of Kerner's "very unreliable ... account", but Bond described the denouement as "brilliantly and subtly done".

[6] Finally, Walklate criticised the book's failure to explore the social issues it raises, for example a women's place in Victorian society, and the impact on those labelled "mad".