Holmes and Norman Shelley as Watson. "The Red Circle" was dramatised for BBC Radio 4 in 1994 by Peter Ling as part of the 1989–1998 radio series starring Clive Merrison as Holmes and Michael Williams as Watson, featuring Joan Sims as Mrs Warren. In 2013, the story was adapted as an episode of The Classic Adventures of Sherlock Holmes, a series on the American radio show Imagination Theatre, with John Patrick Lowrie as Holmes and Lawrence Albert as Watson. Of note This is the last appearance of Inspector Tobias Gregson in Doyle's work. Explanations for this have been a matter of debate for readers. Although Gregson's meeting with Holmes is coincidental, he is swift to grasp the implications of getting his help and claims to have been grateful for his work with the Yard in the past. The Pinkerton detective Leverton is called "the hero of the Long Island cave mystery" by Holmes. But there is no explanation of what the Long Island cave mystery entailed. This is considered by some to be one of untold cases of the Holmesian canon, though it doesn't seem to have involved Holmes. This mystery seems paradoxical because there are no real caves on Long Island, New York, but there are caves on Long Island, in the Bahamas. Howe Street is a creation of Conan Doyle, overlooking Orme Street, which is commonly known as Great Ormond Street located in Central London, northeast from the British Museum. Watson describes Orme as a "narrow thoroughfare" and Howe in possession of "more pretentious houses." References Notes Sources External links produced by Granada Television (1994) Red Circle, The Adventure of the 1911 short stories Short stories adapted into films Works originally published in The Strand Magazine