George Orwell, lamenting the Decline of the English Murder in 1946, drew up a list of murders that were committed in that “great period in murder, our Elizabethan period”, roughly from 1850 to 1925. Surprisingly, the 1860 killing of four-year-old Francis Saville Kent by his 16-year-old half-sister, Constance, was not on his list, perhaps because she did not fit the profile of his “ideal” murderer: male, petit-bourgeois, and fearful of losing his respectability.

Constance, if only by virtue of her age and sex, was hors de combat, although her father, Samuel Kent, frequently suspected, was closer. Kent was an inspector of factories living well beyond his means. His private life did not bear looking into too closely, his respectability was a tenuous concoction of smoke and mirrors. He was a partner in a firm of dry-salters, whose father-in-law, a fellow of the Royal Society of Antiquaries, got him a more “genteel” position inspecting factories. His wife, Mary Anne, gave birth to four children in five years, and then, according to Kent, began showing signs of mental disturbance. Not enough disturbance, however, for him to forgo his conjugal rights: in the next 10 years she bore him six more children, four of whom died in infancy. By the time of her death in 1852 she had long been supplanted by Mary Pratt, the governess, not only in caring for the children, but also in running the house and in Kent's bed.

He was summoned by the Board of Factory Commissioners to respond to whispers of his wife's mental state and his relationship with the governess. His explanations were accepted, but he failed to win hoped-for promotion, and was later summoned again. By the time he married the governess in 1853, local gossips were busy with the fact that the Kents couldn't keep servants. At the time of Francis Saville's death, there were only three for a family of nine. While popular consensus after the death put Kent's income at £800, Summerscale's research shows that it was £500 - far too little for the large house and appurtenances of upper-middle-class life to which Kent clung. This was a house hiding typically Victorian secrets, revolving around sex and money, respectability and its opposite - exposure and shame.

These latter came swiftly when the toddler was found one morning, thrust down the servants' privy, probably smothered, his throat slashed to the spine. Circumstances made an intruder unlikely, and suspicion shone a harsh light on the more than dubious household. After a bungled local investigation, Inspector Whicher of Scotland Yard's “Detective Department” was sent for. He suspected Constance and she was arrested. However, no evidence could be found to back up his supposition and she was never charged. Although Whicher continued to have the support of his superiors, middle-class newspaper readers were horrified that a working-class man, a detective (in effect, a servant), had been in a position to detain a girl of their own class. His career never recovered, even after Constance, living in a high-church retreat in Brighton, confessed a full five years later, specifically exonerating her father, who had frequently been put forward by the newspapers as the murderer. (The suggestion was that, falling back on old habits, he was sleeping with the nursemaid; the child had woken and seen them and been accidentally killed in an attempt to silence him. Charles Dickens, a great murder-fan, whole-heartedly supported this theory.)

Times Archive, 1860: The recent murder at Road-hill House

A crime has just been committed which for mystery, complication of probabilities, and hideous wickedness is without parallel

• Leading article: Road child murder

• The case of Constance Kent

• Constance Kent indicted

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Summerscale has done excellent research in ferreting out the details of this curious case. Because Constance pleaded guilty there was no further investigation for 150 years, and aficionados have been able to argue both sides with equal facility. She has read copiously both in the newspapers of the period and in the fiction that eagerly built on the telling details - Dickens used an episode from Constance and her brother William's childhood for the Landless siblings in The Mystery of Edwin Drood, Wilkie Collins not only highlighted the suspicions surrounding Constance's missing nightgown in The Moonstone, but drew a compelling portrait of the working-class detective stumbling into upper-class life.

My only caveat is that Summerscale perhaps fails to recognise the formulaic element of crime-writing of the period - much of the newspaper reporting, many of the ballads and broadsheets, used a limited and repetitive range of stock phrases for every murder. At the same time, she lets truly unusual incidents pass with little comment. At Constance's sentencing after her confession, for example, the fact that the judge wept when he passed sentence is given the same weight as the phrase he finished with: “And may God have mercy on your soul.” The latter, of course, was standard; the former was an almost shocking indication of the passionate involvement people felt with this sullen, silent, unlovely and unloved girl.

Summerscale has come up with, to me, a new solution to the puzzle, and in doing so, has produced a book that deepens and expands the knowledge of what one would have thought was an already over-examined case: a remarkable achievement.

The Suspicions of Mr Whicher by Kate Summerscale
Bloomsbury £14.99 pp384

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