A A Milne (1882-1956)
The Red House Mystery (1922)
This novel is Golden Age detective story from the author of Winnie the Pooh.
http://en.wikipedia.org/wiki/The_Red_House_Mystery
“The Red House Mystery is a "Whodunit" mystery novel by A. A. Milne, published in 1922. It was Milne's only mystery novel; he is better known for his children's stories and poems.
The setting is bachelor Mark Ablett's English country house loaded with guests, including a British major, a wilful actress, and a young jock athlete. Mark's long-lost brother Robert, the black sheep of the family, arrives from Australia and is found murdered in a locked room. Mark Ablett has disappeared so Tony Gillingham and his friend Bill decide to investigate, progressing almost playfully through the novel while the clues mount up the theories abound.”
NB After I had formatted the book I realised that DR Drib has already uploaded an LRF version. The main difference is that mine has corrected a couple of typos and features emdashes.