Henry Holt and Company, 1983.
Review published Feb 2017.
Chief Superintendent Henry Tibbett, CID, and his wife Emmy, are invited to a meeting of the mystery writers belonging to the Guess Who club on the Isle of Wight estate of the publisher Sir Robert Oppenshaw. One of the guests falls off a cliff, and a classic English country house mystery is set into motion.
Tibbett is never officially involved, because the local coroner's jury returns a verdict of accidental death. Tibbett is the only one who knows it was murder, so he pokes and snoops and uncovers a delightfully snarled plot filled with inheritance and precise timing.
This was the first novel by Patricia Moyes I've read, and it reminded me of other writers of this ilk -- Dorothy Sayers, Ngaio Marsh, etc. I'll be looking for Moyes' name in the bookstores from now on.