Sir Henry Duncan Littlejohn (8 May 1826 – 30 September 1914) was a Scottish surgeon, forensic scientist and public health pioneer. He is also known as an inspiration for the literary character Sherlock Holmes.
Henry Littlejohn was born in Edinburgh in 1826 to Isabella Duncan and Thomas Littlejohn, a confectioner of 33 Leith Street. He began his studies at the Perth Academy, before attending the Royal High School, Edinburgh. He studied medicine at the University of Edinburgh, graduating with distinction in 1847. He was taught surgery by Alexander Monro and Robert Halliday Gunning.
Littlejohn served as Edinburgh's first Medical Officer of Health (1862–1908), introducing model sanitation improvements and the legal requirement to notify cases of infectious diseases. He contributed significantly to the public health movement in Edinburgh and to public health administration and also to urban management. He was assisted in later years by Dr Thomas William Drinkwater FRSE. Littlejohn also co-founded the Royal Hospital for Sick Children in Edinburgh.
Serving as Edinburgh's Police Surgeon from 1854 and as Medical Advisor to the Crown in Scotland in criminal cases, he was often called upon as an expert witness. From 1862 he was Edinburgh's first Medical Officer of Health.
A kirk elder at the High Kirk of Edinburgh, Littlejohn filled several prominent posts in public life, including nine years on the board of the Royal Infirmary of Edinburgh, president of the Royal College of Surgeons of Edinburgh (1875–76), president of the Medico-Chirurgical Society of Edinburgh (1883–85), and president of the Royal Institute of Public Health (1893).
Although Arthur Conan Doyle primarily credited Joseph Bell as being the source of inspiration for his character Sherlock Holmes, he also cited Henry Littlejohn as being a contributing influence. Littlejohn, as a forensic expert involved in police investigations, appears to have been joined by Bell on several investigations; furthermore, Littlejohn taught Doyle forensic medicine when Doyle was studying at the medical school of the University of Edinburgh.
Henry Littlejohn was knighted in 1895 by Queen Victoria.
He died at Benreoch, near Arrochar in Argyll in 1914, and was interred at the Dean Cemetery in Edinburgh. His grave is on the edge of the southern path towards the west end. He is buried with his wife, Isabella Jane Harvey, and their children. Sir Henry was the father of Henry Harvey Littlejohn (1862–1927) (normally just called Harvey Littlejohn during his life but posthumously largely called Henry) who followed in his father's footsteps and continued his adoption of tangential thinking to resolve investigations.
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- Edinburgh and Leith Post Office Directory 1863-64