resulting analytical short-cut was christened at Bletchley Park Parkerismus after Reg Parker, who had, through his meticulous record-keeping, spotted this phenomenon. The re-use of a permutation in the German Air Force METEO code as the Enigma stecker permutation for the day. Mavis Lever, a member of Dilly Knox's team, recalled an occasion when there was an extraordinary message. Postwar debriefings of German cryptographic specialists, conducted as part of project TICOM, tend to support the view that the Germans were well aware that the un-steckered Enigma was theoretically solvable, but thought that the steckered Enigma had not been solved. Crib-based decryption The term crib was used at Bletchley Park to denote any known plaintext or suspected plaintext at some point in an enciphered message. Britain's Government Code and Cipher School (GC&CS), before its move to Bletchley Park, had realised the value of recruiting mathematicians and logicians to work in codebreaking teams. Alan Turing, a Cambridge University mathematician with an interest in cryptology and in machines for implementing logical operations—and who was regarded by many as a genius—had started work for GC&CS on a part-time basis from about the time of the Munich Crisis in 1938. Gordon Welchman, another Cambridge mathematician, had also received initial training in 1938, and they both reported to Bletchley Park on 4 September 1939, the day after Britain declared war on Germany. Most of the Polish success had relied on the repetition within the indicator. But as soon as Turing moved to Bletchley Park—where he initially joined Dilly Knox in the research section—he set about seeking methods that did not rely on this weakness, as they correctly anticipated that the German Army and Air Force might follow the German Navy in improving their indicator system. The Poles had used an early form of crib-based decryption in the days when only six leads were used on the plugboard. The technique became known as the Forty Weepy Weepy method for the following reason. When a message was a continuation of a previous one, the plaintext would start with FORT (from Fortsetzung, meaning "continuation") followed by the time of the first message given twice bracketed by the letter Y. At this time numerals were represented 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