THE mystery of how Sherlock Holmes knew so much about poisons has been cracked in the archives of the Royal Botanic Garden in Edinburgh.
Class rolls dating back to 1877 prove that a surprisingly green-fingered Doyle attended about 60 classes, seven demonstrations and nine excursions.
The 140-year-old records bear the signature of a teenage Doyle, along with the the fact that he missed two classes through illness.
Doyle’s studies went on to play a crucial part in the Sherlock novels as the legendary detective utilised his knowledge of poisonous plants to solve a range of murder mysteries.
The researchers, led by archivist Leonie Paterson, have worked with the National Galleries of Scotland and Edinburgh University Library to piece together the author’s time in the capital.
During his studies at the garden he had access to plants such as opium and belladonna - a deadly nightshade.
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He did not start writing the infamous Sherlock novels until a decade later, but it appears his studies stuck with him.
In A Study in Scarlet, Dr Watson lists Sherlock’s strengths and weaknesses.
He proclaims: “Knowledge of Botany: Variable. Well up in belladonna, opium, and poisons generally. Knows nothing of practical gardening.”
The list is a direct nod to Conan Doyle’s own abilities – during his studies he learned about the uses of plants but was not lectured in practical work.
Dr Elspeth Haston, deputy curator in the Botanics’ herbarium, said: “I think it will surprise a lot of people to know that Conan Doyle studied here.
“It’s a different aspect to his history and sheds a whole new light on his attributes. I’m a huge fan of the Sherlock series and this was a revelation to me – it’s been really interesting to help piece the history together.”