Diogenes Club? Are you Holmesian?
Kim Newman is an interesting author who blends his three interests, (1) 19th and Early 20th Century Literature including "pulp fiction" like horror and hard boiled detective stories, (2) history and (3) the occult in his many novels. He borrows characters and institutions from many 19th Century novels, like Mycroft Holmes and the Diogenes Club from Aurthor Conan Doyle (along with many Holmesian villians), with horror Characters like Doctor Jeckyle and Mr. Hyde from Robert Lewis Stevenson, Count Dracula from Bram Stoker, or the Characters from H.P. Lovecraft's Cthulu tales, as well as classic characters from Kipling, and uses them alongside real historical figures and characters of his own creation in his novels and short stories.
In Newman's novels and stories, a secret cabal within the Diogenes Club has evolved into the highest level of the British Secret Service, into everything from criminal masterminds, espionage in the Great Game and European politics to dealing with the occult. Its players include Charles Beauregard (from 1880's through WWI), Edwin Winthrop (WWI through WWII), Catrione Kay (Post WWI through the 1960's) and Richard Jeperson (1960's and 1970's), along with their sidekicks, friends and lovers, from Danny Dravot (Kipling's the Man Who Would Be King, now a Vampire), Kate Reed, a 19th Century journalist turned vampire, through Genevieve Diodonne, a Vampire from the 1400's.
The first novel of his I read, "Anno Dracula" employed a little "alternative literature" as opposed to "alternative history" - it took place in a London where Professor Von Helsing's merry band had failed, Dracula had more or less "conquered" British society, and much of high and low British society was becoming Vampires. Charles Beuregard, Genevieve Diodonne and Danny Dravot are investigating the "Jack the Ripper" (also known as the "Silver Knife") murders of newborn Vampire harlots (it turns out to be one of the members of Von Helsing's group) on behalf of the Diogenes Club, and in doing so, find the means of taking Dracula down. His second in the series, "The Bloody Red Baron" finds Dracula, now the power behind Kaiser Wilhelm's thrown, employing shape shifting Vampire flyers to overcome the Allies (who also employ Vampires) in WWI. Edwin Winthrop, a human, drinks vampire blood to obtain the necessary skills to overcome the Vampire Red Baron, and defeat Dracula's gambit (a Vampire Winston Churchill is now one of the ruling cabal of the Diogenes Club). A third novel, taking place in post-war italy, depicts the fall of Dracula (murdered by one of his original British get) and the death of Charles Beauregard of old age - he refuses to become a Vampire to extend his life). The two books I am reading now are compilations of short stories about various Diogenes adventures from the 19th Century through the 1970's. Newman is a good author, the adventures remind me of a good 19th Century adventure story like King Solomon's Mines, She, or the Lost World, or sometimes, a good piece of Pulp Fiction, like one of Lovecraft's Cthulu tales, or a Dashell Hammett detective story.