Enigma

could.
    On the train he found an empty compartment and stared at his reflection in the glass, an image which gradually became clearer as the dusk gathered and the flat countryside disappeared, until he fell asleep.
    The main gate to the college was closed. Only the little doorway cut into it was unlocked and it must have been ten o'clock when Kite, dozing beside the coke stove, was woken by the sound of it opening and closing. He lifted the corner of the blackout curtain in time to see Jericho walking into the great court.
    Kite quietly let himself out of the Porter's Lodge to get a better view.
    It was unexpectedly bright—there were a lot of stars—and he thought for a moment that Jericho must have heard him, for the young man was standing at the edge of the lawn and seemed to be listening. But then he realised that Jericho was actually looking up at the sky. The way Kite told it afterwards, Jericho must have stood that way for at least five minutes, turning first towards the chapel, then the meadow, and then the hall, before moving off purposefully towards his staircase, passing out of sight.

Acknowledgements
    I OWE A debt of gratitude to all those former employees of Bletchley Park who spoke to me about their wartime experiences. In particular, I would like to thank Sir Harry Hinsley (Naval Section, Hut 4), Margaret Macintyre and Jane Parkinson (Hut 6 Decoding Room), the late Sir Stuart Milner-Barry (former head of Hut 6), Joan Murray (Hut 8) and Alan Stripp (Japanese ciphers).
    Roger Bristow, Tony Sale and their colleagues at the Bletchley Park Trust answered my questions with great patience and allowed me to wander about the site at will.
    None of these kind people bears any responsibility for the contents of this book, which is a work of the imagination, not of reference.
    For those readers who would like the facts on which this novel is based, I strongly recommend Top Secret Ultra by Peter Calvocoressi (London, 1980), Codebreakers edited by F. H. Hinsley and Alan Stripp (Oxford, 1993), Seizing the Enigma by David Kahn (Boston, USA, 1991), The Enigma Symposium by Hugh Skillen (Middlesex, two volumes, 1992 and 1994), The Hut 6 Story by Gordon Welchman (New York, 1982) and GC//Q by Nigel West (London, 1986).
    Details of the action in the North Atlantic are drawn from the original, decoded signals of the U-boats, held at the Public Record Office in London, and also from Convoy by Martin Middlebrook (London, 1976) and The Critical Convoy Battles of March 1943 by Jiirgen Rohwer (English translation, London, 1977).
    Finally, I would like to record my special thanks to Sue Freestone and David Rosenthal, neither of whom ever lost faith in Enigma, even on those occasions when it was a mystery to its author.

    Robert Harris
    June 1995