[6] Other novels written by Newman which share the same fictional setting or have been incorporated into it via retroactive continuity include Professor Moriarty: The Hound of the D'Urbervilles, Angels of Music, The Secret of Drearcliff Grange School (spinning out of and expanding upon a story which first appeared in Mysteries of the Diogenes Club) and The Haunting of Drearcliff Grange School.
[7] Published in 2006 (ISBN 9781932265170), this collection deals with the Club's exploits during the 1960s and 1970s, with the exception of "Swellhead", which is set in the modern day.
The stories in this collection focus on 'Most Valued Member' Richard Jeperson, who is notable for his flamboyant dress sense and sensitivity to psychic and paranormal phenomena, a homage to various television characters from the Seventies, in particular Jason King (of Department S and Jason King), John Steed and the Third Doctor.
Published in 2007 (ISBN 9781932265279), the second collection of stories covers the period of time between the Victorian era and the beginning of the 1970s, featuring original Diogenes Club head Charles Beauregard and his protégé Edwin Winthrop, as well as recurring Newman character Geneviève Dieudonné.
Published in 2010 (ISBN 9781932265309), the final Diogenes Club collection visits all of the time periods and protagonists featured in previous collections, culminating in "Seven Stars", which tracks the progress of the Jewel of Seven Stars, a powerful magical artifact which originates in the Bram Stoker novel of the same name and which interacts with all the major Diogenes Club characters throughout history.