Calculating how much of his life has been devoted to Sherlockian endeavours is as scary to David as calculating how much money he has spent on wine - this week.
But you don't get to be one of the leading experts on Sherlock Holmes by simply speed reading 'Conan Doyle for Dummies' and wearing a Deerstalker round the house - that's just part of what it takes. Add on the time David spends developing and writing his Johnny One Eye tales, and the endless hours of presentations, editorial duties, and social butterflying, and there just isn't much time left in the day to be working on other characters.
However, David is also the creator of the following...
Introducing Luther Darke

Luther Darke is a Victorian puzzle-solver. Darke, the elder son of a duke, passed over the title and the family home to his younger brother. Ducal respectability and responsibility are abhorrent to his bohemian soul. Although he is a wealthy man by inheritance and investment, he has a desire to make a name for himself as an artist. He also has a passion for the curious, the unknown, the mysterious the puzzle which baffles others. In helping Scotland Yard with one of their unsolved crimes, he came into contact with Inspector Edward Thornton. This began a growing relationship between the two men and Thornton has consulted Darke on several occasions since. Darke lives in Manchester Square, off Oxford Street with his manservant George and a cat called Persephone. His lover, Carla, is a writer and a feminist.
Much of this is explained in the first story.
Darke was created by David for the SHERLOCK magazine and has appeared in six stories. (The Curzon Street Conundrum, The Darke Chronicles, The Enigma of the Griswold Phantom, The Mystery of the Missing Black Pearl, The Riddle of the Visiting Angel, and The Vampire Murders Intrigue)
The first tale, The Curzon Street Conundrum, was also published in Murder Through the Ages, a collection of historical mysteries published by Headline in 2000.
The Curzon Street Conundrum is available as a PDF download if you'd care to read it. Go to the 'contact' page and it can be found in the DSDownloads area, along with all manner of other good things.