How would Sherlock Holmes approach this case?

by Matthew D. Hall

It seems inevitable that when newspaper reports of events at the Blue John Gap in North-West Derbyshire appeared in the newspapers around May 1907, that they would have come to Sherlock Holmes's attention. It seems unlikely that Holmes received copies of the Castleton Courier that reported the hundreds of locals that banded together to stop up the entrance of the tunnel (after all, Castleton only had a population of 547 in 1901). However, while established in his “retirement” upon the Downs five miles from Eastbourne, the London papers delivered to him may well have carried reports abstracted from the Derbyshire papers.

We know that in retirement Holmes maintained a library in the garret of his villa, and given the singular nature of the story of the “Terror of Blue John Gap,” he may well have chosen to enter this case in his commonplace books (and of course to cross-reference the entry). While we often associate Sherlock Holmes with detection and resolution of crime, the cases reported by Dr. John Watson regularly resolved “supernatural” phenomena to natural and material explanations.

It is only through a confidence in, and understanding of, the diversity of fauna past and present that Holmes could remain steadfast when he states in the Hound of the Baskervilles that he “hitherto confined my investigations to this world.” Indeed, in “The Adventure of the Sussex Vampire,” Watson provides a glimpse into the “great index volume” Holmes maintained for the letter V with a “record of old cases, mixed with the accumulated information of a lifetime,” and entries are revealed for: Voyage of the Gloria Scott; Victor Lynch, the forger; Venomous lizard or gila; Vittoria, the circus belle; Vanderbilt and the Yeggman; Vipers; Vigor, the Hammersmith wonder; Vampirism in Hungary; Vampires in Transylvania.

Of the nine entries made by Holmes, two relate to exotic terrors of the natural world. We can be sure that this accumulation of knowledge served Holmes well, and ensured a confidence in natural solutions. The gigantic hound in Hound of the Baskervilles was achieved through selective breeding and the application of luminescent chemicals. When faced with the evidence of an unknown animal in “The Crooked Man,” Holmes recognized that its paw prints were caused by “neither dog, nor cat, nor monkey, nor any creature that we are familiar with,” but used quantitative measurements to divine the length and stride of the creature that was revealed to be an ichneumon (or mongoose, which indeed Watson was familiar with upon sighting it). More terrifying creatures were addressed by Holmes, including the “repulsive story of the red leech,” and perhaps more pertinently the giant rat of Sumatra, “a story for which the world is not yet prepared.”

Having established that the resolution of cases of superstition and terror were well within the remit of Holmes’s expertise, we turn to ask whether Holmes could have looked into this particular case. Holmes maintained a degree of activity after his “retirement” in 1903, and it is generally agreed that he was highly active during World War 1 (1914-1918, beginning with the deceptively titled story “His Last Bow”). In July 1907 (just two months after the conclusion of the Blue John Gap episode), Holmes was induced to solve “The Adventure of the Lion’s Mane” (yet another “murder” that is determined to be caused by a sea creature).

It is related in “The Adventure of the Lion’s Mane” that Watson made occasional weekend visits to Holmes. Watson’s practice (as of 1902) was on Queen Anne Street, Marylebone, just over 2 miles from South Kensington (perhaps Hardcastle’s residence of “Upper Coventry Flats” was on Coventry Street, South Kensington), and the physicians may have been acquainted professionally or through a common club. Faced with a mystery worthy of his closest friend, it seems entirely reasonable that Watson came to Sussex from London armed with the letter found among his young colleague Dr. James Hardcastle’s possessions upon his death on February 4th, 1908.

Recognizing the original events of Blue John Gap indexed in his commonplace books, Holmes would have found the story and the open question of the source of terror irresistible. The twin tools of intellectual evaluation and forensic examination of the scene would be required. First, leveraging his records and his brain attic, Holmes would have turned inwards as he weighed up the facts of the letter while smoking copious quantities of tobacco. Could an enormous beast exist? Certainly the improbable is not impossible. Could Hardcastle’s tuberculosis have resulted in psychosis? This is exceedingly rare. Could the anxiety of an infection with a disease with a high mortality rate have affected Hardcastle? This is confirmed by Hardcastle in his own diary entries.

Deep reflection on the diary entries and the newspaper account of the reaction of the “country people” who blocked up the entrance to the tunnel, left Holmes unable to refute completely the existence of “some inconceivable monster” (something utterly un-English!!).

This left Holmes with the need to visit the scene and practice the arts of observation and investigation: “Data, data, data, I cannot make bricks without clay.” The journey to North-West Derbyshire was a relatively long one, and Castleton was seven miles from the nearest railway station of Chapel-en-le-Frith. That an investigation of the circumstances took place in North-West Derbyshire is revealed in the published story: “I may add that the visit of the deceased to Allerton’s Farm, and the general nature of the alarm there … . have been absolutely established.”

As an aside, it may be that Holmes assigned his friend John Watson with investigations in London, as the search to find Seaton there “failed.” Tempering Holmes’s productive interviews with locals would have been the lost opportunity to examine direct evidence such as ovine disjecta membra. Holmes was particularly skilled at analyzing impressions in the earth. James F. O’Brien points out that footprints are mentioned in twenty-six of sixty published cases, but weather would have erased the huge depressions by the time the investigation was launched. Likewise, while there is no report in the canon of Holmes turning to coprology, the scat of the Terror would have been insightful. With the Blue John Gap stopped up, no direct evidence was available.

Holmes returned to Sussex without a clear resolution of the case. The account of the Terror was from a witness who was intellectually credible but potentially unreliable (Hardcastle was referred to the local mad doctor), but it was supported by the reaction of locals to the disappearance of sheep and Armitage. Holmes’s knowledge was accumulated based on the belief that “There is nothing new under the sun,” but the Terror of Blue John Gap could only tolerate a pitch-black world. As a final option, enquiry may have been made with Mycroft on whether the government’s clearinghouse had detected communication on dreadful monsters. There is the slight chance that the truth of the Terror of Blue John Gap was another story for which the world was not yet prepared, and the Holmes brothers agreed to withhold the details.

What could Holmes do with a sensational account without resolution? In “The Yellow Face,” Watson makes it clear that “where he [Holmes] failed it happened too often that no one else succeeded, and that the tale was left forever without a conclusion.” Following investigation and without resolution, Watson passed the details of Hardcastle's account with Holmes’s confirmation of the general circumstances along to his literary agent, who made arrangements to publish it in the Strand Magazine in August 1910.


General references:

Vernon Rendall, “The Limitations of Sherlock Holmes.” Baker-street studies, edited by H. W. Bell, Constable & Co., 1934.

James F. O’Brien, The Scientific Sherlock Holmes, 2013, Oxford University Press.

Maria Konnikova, How To Think Like Sherlock Holmes, 2013, Penguin Books.

Brad Keefauver, “The Elementary Methods of Sherlock Holmes,” 1987, Magico Magazine.

Specific references:

Population of Castleton:

Untold tales: Philip K. Jones, "Codes for The Apocrypha and The Untold Tales,” The Shoso-in Bulletin, 2004, Volume 14, 103-114.

Castleton and the rail journey: "Castleton, Derbyshire: 19th Century Directory Transcripts," Kelly's Directory of the Counties of Derby, Notts, Leicester and Rutland, (London, May 1891), 73-75. (


Matthew D. Hall is an Australian by origin, but is now American, residing in Maryland where he works at the National Institutes of Health. He has long been a devotee of Sherlock Holmes, but only discovered the Sherlockian and Doylean worlds about five years ago. His home scion is the Red Circle.