For the collector of Agatha Christie’s works, her participation in the Detection Club resulted in several original writings that were contributed to Detection Club stories, and thus should be part of any complete Christie collection.
The Detection Club was founded in 1930 by a group of 26 authors, including Agatha Christie, Dorothy Sayers and G. K. Chesterton - the group’s first president. Christie would assume the presidency in 1957 and she held it until her death in 1976. It’s original purpose was as a support group that would meet over dinner. But the group also agreed to adhere to some basic principles in how to write detective fiction.
In its formative years Dorothy Sayers decided that the club should work on various collaborative projects. Members co-wrote innovative ‘round robin’ mystery novels, starting with The Floating Admiral (1931) in which each chapter is written by a different author, 12 in all. This was the only collaborative book that Christie contributed original material to - Chapter IV “Mainly Conversations” and a solution at the end of the book.
The Floating Admiral was published in the UK by Hodder & Stoughton, London in 1931 (undated 1st edtion) and in the US by Doubleday, Doran & Co, NY dated 1932, as part of the ‘Crime Club, Inc’ imprint. The first edition hardback books can be found affordably (value UK $50, US $30), but jacketed copies are quite rare. The US version in a very good jacket is worth $1,000, while the rare UK version could easily command $3,000 (or what the buyer can bear). Compared to Christie's individual works, these books are quite affordable on a relative basis.
The BBC also hired the Detection Club to create radio plays. In 1930, Sayers, Christie, Berkeley and others wrote successive installments of a whodunit titled Behind the Screen. Each author read out their chapter in a live broadcast followed the week later by a printed version in the BBC weekly magazine, The Listener, and the subject of a future article.
These stories were first printed in book form in 1983 by Victor Gollancz Ltd, London and at the same time by Harper & Row, New York. Both are very affordable and valued at $20 - $50, in jacket, depending on condition.
Since Christie did not provide any original story material to several of the Detection Club books newer versions have had material added so that Christie’s name can be added to the cover as part of a marketing ploy. In the 2013 edition of the Detection Club's Six Against The Yard, Harper Collins added an essay Christie wrote in 1929 for a newspaper about the Croydon Poisonings to enable this new edition to carry Christie's name on the cover.
While Ask A Policeman was also not contributed to by Christie, there is a newer version of the book that contains a previously unprinted article, as a preface, by Agatha Christie titled ‘Detective Writers in England’ in which she discusses her approach to writing and her fellow writers in the Detection Club. Neither of these books would be viewed as collectible, but for Christie fans who want to read all she wrote, they are necessary acquisitions and very affordable at basically used book rates.