Six "perfect murders" by Margery Allingham, Dorothy L. Sayers, and other Golden Age Mystery authors of the Detection Club—plus an essay by Agatha Christie.   Founded in England in the 1930s, the Detection Club brought together an impressive array of Golden Age Mystery authors. Their projects included The Floating Admiral, a whodunit in which twelve different writers contributed individual chapters, as well as Ask a Policeman, another collaboration in which the mystery writers swapped detectives to solve a murder.   In Six Against the Yard, a half dozen mystery masters—Margery Allingham, Father Ronald Knox, Anthony Berkeley, Russell Thorndike, Dorothy L. Sayers, and Freeman Wills Crofts—each create a perfect crime, a seemingly unsolvable mystery. The stories are then analyzed by Ex-Superintendent Cornish, C.I.D., a real-life retired police detective, to see if they would indeed stump Scotland Yard. This edition also features an afterword by inaugural Detection Club member Agatha Christie on a true unsolved case of arsenic poisoning in Britain in 1929.