The journalist A.B.Cox, who wrote for Punch, the Daily Telegraph and the Sunday Times wrote both as Anthony Berkely and Francis Iles. The latter pseudonym is perhaps better known, one book inspiring the Hitchcock classic Suspicion. As Anthony Berkely, Cox wrote the Roger Sheringham stories, a classic product of the Golden Age of detective writing (Cox was born in 1893, only three years after Agatha Christie).
The Poisoned Chocolates Case has always been one of my favourite of the Sheringham books. It gently satirises the cult of the gentleman detective, each member of his "Crime Circle", a society of amateur sleuths coming up in turn with a different but perfectly plausible explanation of the same facts, and each fingering a different murderer. It is perhaps unique in the genre in featuring a gentleman detective who can actually get it wrong.
Berekeley's books are often more complex than one finds with those of his contemporaries. The morality is often far from clear-cut, with likable murderers and detestable victims. He also plays narrative tricks, such as writing what does not feel like a crime novel at all and suddenly turning it midstream into a murder story. He did incidentally have a very good knowledge of police procedures from his journalistic activities and two of his novels, The Wychford Poisoning Case and The Anatomy of Murder are based on real life cases.
Happily some of his books have now been reprinted, and are also well worth looking out for in second hand bookshops. The Silk Stocking Murders and Murder in the Basement are also on my bookshelves and can be strongly recommended.