I could be reinventing the wheel but have thought it might be of interest to regular or occasional readers of A Crime is Afoot.
The Notting Hill Mystery by Charles Felix, dating back to 1862, preceded The Moonstone by some years. (Thank you Kerrie)
The author Julian Symons identified The Notting Hill Mystery as the first detective novel in 1972, calling its primacy “unquestionable” and its plot “strikingly modern”. The British Library first made the novel available via print-on-demand last March, as part of a collection of hundreds of 19th century novels. While most sold just two to three copies apiece, The Notting Hill Mystery took off following a glowing write-up in the New York Times which identified Adams as its author and described its ending as both “ingenious and utterly mad”, selling hundreds of copies and prompting the library to issue its new trade edition this month.
Read the complete article at The Guardian here.
For additional information:
Maybe as Les éditions de Londres says: “Not so popular when released, forgotten a few years later, fallen into oblivion for over hundred years, “The Notting Hill mystery” can still be seen technically as the first detective novel. But, as we said earlier, it is not so important. The true contribution of “The Notting Hill mystery” to the history of detective and crime novels it its novelty, it utter originality and how ahead of its time it was.”