492 | NOTES TO PAGES 94–109
- T. Hughes and J. Costello, Battle of the Atlantic, Doubleday (1977).
- W. G. Welchman, The Hut Six Story: Breaking the Enigma Codes, Allen Lane (1982), p. 168.
CHAPTER 11 BREAkING mACHINES wITH A PENCIl (BATEy)
- Letters from Peter Twinn to Jack Copeland (28 January and 21 February 2001).
- Hugh Foss mentioned several such cribs in his ‘Reminiscences on Enigma’, in Smith & Erskine (2001),
p. 45; another is described in the section ‘The race to break Enigma’. - See M. L. Batey, Dilly: The Man who Broke Enigmas, Dialogue (2009), pp. 68–72; the complete 1930
operator’s manual with the crib is set out in Appendix I. - W. Kozaczuk, Enigma: How the German Machine Cipher Was Broken, and How It Was Read by the
Allies in World War Two (transl. C. Kasparek), Arms and Armour Press (1984), p. 236. - A. D. Knox, ‘Warsaw’, NA HW25/12.
- W. G. Welchman, The Hut Six Story: Breaking the Enigma Codes, 2nd edn, M&M Baldwin (1997), p. 34.
- Letter from Knox to Alastair Denniston, NA HW14/1.
- M. Rejewski, Memories of My Work at the Cipher Bureau of the General Staff Second Department
1930–1945, Adam Mickiewicz University in Poznán (2011), p. 132. This book was published to
commemorate the thirtieth anniversary of Rejewski’s death; written in 1967, it was deposited in the
Wojskowy Instytut Historyczny, and is now published with an English translation. - Kozaczuk (Note 4), p. 97.
- Letter from Knox to Denniston, NA HW25/12.
- They were inapplicable except in the case of the cipher key codenamed ‘Yellow’ at Bletchley Park. On
1 May 1940 Yellow was being used in the short-lived Norwegian campaign, and for a while it retained
the old method of encoding the indicators. - A. M. Turing, ‘Prof ’s Book’, NA HW25/3 (under the title ‘Mathematical theory of ENIGMA machine
by A M Turing’). A digital facsimile of Turing’s typescript is available in The Turing Archive for the
History of Computing (http://www.AlanTuring.net/profs_book). - Birch’s letter is in C. Morgan, ‘N.I.D. (9) Wireless intelligence’, NA ADM223/463, p. 39; pages 38–9
contain Morgan’s account of Operation Ruthless and include Fleming’s memo to the Director of Naval
Intelligence. - C. Caslon, ‘Operation “Claymore”—report of proceedings’, NA DEFE2/142.
- Batey (Note 3), p. 130.
- Letter from Knox to Stewart Menzies, NA HW25/12.
- Letter from Birch to Edward Travis, quoted by A. P. Mahon, ‘History of Hut 8 to December 1941’, in
The Essential Turing, p. 287. - J. Murray (née Clarke), ‘Hut 8 and Naval Enigma, Part I’, in Hinsley & Stripp (1993), 113–18.
- On Railway Enigma, see F. Weierud, ‘Railway Enigma and other special machines’ (http://
cryptocellartales.blogspot.co.uk/2013/05/railway-enigma-and-other-special.html) and D. Hamer, G.
Sullivan, and F. Weierud, ‘Enigma variations: an extended family of machines’, Cryptologia, 22 (1998),
211–29. - J. H. Tiltman, ‘Some reminiscences’, in the US National Archives and Records Administration, RG 457,
entry 9032, Historic Cryptographic Collection, pre-World War I through World War II, no. 4632, p. 16. - Turing (Note 12), pp. 31 and 60.
- P. Twinn, ‘The Abwehr Enigma’, in Hinsley & Stripp (1993).
- J. K. Batey, M. L. Batey, M. A. Rock, and P. F. G. Twinn, ‘G.C. & C.S. Secret Service Sigint Vol. II:
Cryptographic systems and their solution—I Machine cyphers’, NA HW43/7.
CHAPTER 12 BOmBES (COPElAND, wITH VAlENTINE AND CAUGHEy)
- I am grateful to Ralph Erskine and Edward Simpson for information, comments, and suggestions.
- A. G. Denniston, ‘How news was brought from Warsaw at the end of July 1939’ (May 1948), NA
HW25/12, p. 4. (Published with an editorial introduction and notes in R. Erskine, ‘The Poles reveal