Cryptanalysis of the Enigma by the letters on the top row of the Enigma keyboard. So, "continuation of message sent at 2330" was represented as "FORTYWEEPYYWEEPY". "Cribs" were fundamental to the British approach to solving Enigma keys, but guessing the plaintext for a message was a highly skilled business. So in 1940 Stuart Milner-Barry set up a special "Crib Room" in Hut 8. Foremost amongst the knowledge needed for identifying cribs was the text of previous decrypts. Bletchley Park maintained detailed indexes of message preambles, of every person, of every ship, of every unit, of every weapon, of every technical term and of repeated
The World That Never Was as "intriguing, provocative and written with a novelist’s eye for detail ... an engrossing journey". In "The Guardian", anarchist writer Stuart Christie noted the relevance of the book's themes to contemporary tactics in policing and the Metropolitan Police Service's reluctance to make public files from the 1890s. Francis Wheen, writing in the "Financial Times", wrote that the book was "exhilarating" and questioned whether "the world that never was – one ignoring borders, and divisions of class and religion – [might] resemble the world as it might one day be"; while Peter Preston of "The Observer" described Butterworth's story as one