always to the full satisfaction of the perpetrator." Guns, knives, garrottes, tripwires, blunt instruments, and even a hatchet were also used, but "Christie never resorted to elaborate mechanical or scientific means to explain her ingenuity," according to John Curran, author and literary adviser to the Christie estate. Many of her clues are mundane objects: a calendar, a coffee cup, wax flowers, a beer bottle, a fireplace used during a heat wave. According to crime writer P. D. James, Christie was prone to making the unlikeliest character the guilty party. Alert readers could sometimes identify the culprit by identifying the least likely suspect. Christie mocked this insight in her foreword to Cards on the Table: "Spot the person least likely to have committed the crime and in nine times out of ten your task is finished. Since I do not want my faithful readers to fling away this book in disgust, I prefer to warn them beforehand that this is not that kind of book." On Desert Island Discs in 2007, Brian Aldiss said Christie had told him she wrote her books up to the last chapter, then decided who the most unlikely suspect was, after which she would go back and make the necessary changes to "frame" that person. Based upon a study of her working notebooks, Curran describes how Christie would first create a cast of characters, choose a setting, and then produce a list of scenes in which specific clues would be revealed; the order of scenes would be revised as she developed her plot. Of necessity, the murderer had to be known to the author before the sequence could be finalised and she began to type or dictate the first draft of her novel. Much of the work, particularly dialogue, was done in her head before she put it on paper. In 2013, the 600 members of the Crime Writers' Association chose The Murder of Roger Ackroyd as "the best whodunit... ever written". Author Julian Symons observed, "In an obvious sense, the book fits within the conventions... The setting is a village deep within the English countryside, Roger Ackroyd dies in his study; there is a butler who behaves suspiciously... Every successful detective story in this period involved a deceit practised upon the reader, and here the trick is the highly original one of making the murderer the local doctor, who tells the story and acts as