For Gordon Welchman and his family
Gordon Welchman:
Bletchley Park’s Architect of Ultra Intelligence
This edition published in 2014 by Frontline Books,
an imprint of Pen & Sword Books Ltd,
47 Church Street, Barnsley, S. Yorkshire, S70 2AS
www.frontline-books.com
Copyright © Joel Greenberg, 2014
Foreword © Rosamond Welchman, 2014
Appendix 2 © Frank Carter, 2014
The right of Joel Greenberg to be identified as the author
of this work has been asserted by him in accordance with the
Copyright, Designs and Patents Act 1988.
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Contents
List of Plates
Foreword
Preface
Acknowledgements
Prologue
Chapter 1
Origins: From Algebraic Geometry to Cryptography
Chapter 2
Bletchley Park: The First Four Months
Chapter 3
The Ultra Architect
Chapter 4
Turing, the Bombe and the Diagonal Board
Chapter 5
Expansion and Consolidation
Chapter 6
The Americans
Chapter 7
Bletchley Park: The Last Two Years
Chapter 8
Post-War and the Birth of the Digital Age
Chapter 9
Writing The Hut Six Story
Chapter 10
Persecution and Putting the Record Straight
Epilogue
Appendix 1
A Beginner’s Guide to Enigma and the Bombe
Appendix 2
Enigma and the Bombe in Depth by Frank Carter
Appendix 3
A Comedy of Errors
Appendix 4
German Air Force/Army Keys Identified and Broken
Appendix 5
Letter from Sir Peter Marychurch
Appendix 6
Welchman’s Publications
Notes
Bibliography
Plates
Plate 1:
GW as a young boy in Bristol; GW while a student at Marlborough College. (both Welchman Family)
Plate 2:
GW’s father William Welchman, Archdeacon of Bristol; GW’s brother Eric, one of the first British officers to be killed in WWI; GW playing hockey for Cambridge Wanderers around 1930; GW during the Cambridge University expedition to Spitzbergen, Norway, in 1932. (all Welchman Family)
Plate 3:
GW with his father and sister Enid at his mother’s funeral in 1938; GW’s marriage to his first wife, Katharine Hodgson, in 1937. (all Welchman Family)
Plate 4:
Bletchley Park, home to the Leon family from 1882 to 1937 (Bletchley Park Trust); Alastair Denniston (Bletchley Park Trust); Edward Travis. (Author’s collection)
Plate 5:
The standard three-wheel Enigma machine as used by the German Army and Air Force. (Bletchley Park Trust)
Plate 6:
Inside the Enigma machine (Bletchley Park Trust); General Heinz Guderian in his command vehicle in 1940 with an Enigma machine. (Bundesarchiv, Bild 101I-769-0229-12A/Borchert, Erich/CC-BY-SA)
Plate 7:
Dispatch riders who delivered intercepted Enigma messages to BP (Bletchley Park Trust); rare wartime photo of some of the original wooden huts. (Courtesy Dr Angela Noble, whose parents Bill Holland and Vera, née Haskell, worked at BP)
Plate 8:
Hut 6 Machine Room in Block D (Crown © reproduced by kind permission of Director GCHQ); Hut 6 structure chart. (TNA HW14/4)
Plate 9:
Hut 6 Control Room in Block D; boxes holding some of the 2 million Hollerith punch cards processed weekly in Block C. (both Crown © reproduced by kind permission of Director GCHQ)
Plate 10:
‘Cobra’ high speed four-wheel bombe attachments; bombes under construction at BTM’s Letchworth factory. (both Crown © reproduced by kind permission of Director GCHQ)
Plate 11:
The British Typex cipher machine, modified to replicate an Enigma machine; prototype of the RM-26, designed by Welchman as a replacement for the Typex; a four-wheel bombe. (all Crown © reproduced by kind permission of Director GCHQ)
Plate 12:
British, American and Canadian participants in the secret J.A.C. Conference held on 13 March 1944 at Arlington Hall, Virginia. (Author’s collection)
Plate 13:
GW while manager of Ferranti Electric Inc. circa 1957 (Author’s collection); GW with his second wife, Fannie Hillsmith (Welchman family); GW while visiting his daughter Ros in Paris in 1972 (Welchman family); GW with his third wife Teeny and her son Tom in 1972. (Welchman family)
Plate 14:
Bletchley Park in the early 1970s (The Times); Diana Lucy. (Author’s collection)
Plate 15:
GW with MITRE colleagues Bobbie Statkus and Bob Coltman. (picture used with the permission of the MITRE Corporation. Copyright © The MITRE Corporation. All Rights Reserved); GW with former BP colleague William Bundy. (picture used with the permission of William Adams)
Plate 16:
GW on holiday with Teeny in the Virgin Islands at the end of March 1985 (Welchman family); GW’s son Nick in 2011. (Author’s collection)
Foreword
Unlike my brother Nicholas Welchman, my sister Susanna Griffith and I were born too late to have any direct memory of my father’s work at Bletchley Park. During my childhood Dad’s war work was a mere rumour in our family – a hint that he had done something important during the war that we couldn’t talk about. I was a sceptical child and did not totally believe this. When the secret was let out and Dad wrote his book, The Hut Six Story, it was a revelation to me, and something of a surprise. I was very fortunate to help Dad in his last year of life with his final paper on his codebreaking experience, which made those years more real to me. In 2001 I visited Bletchley Park – not nearly as developed then as it is now – with my son Daniel Tischler. We were lucky to hear John Herivel give a talk on the occasion of the opening of an exhibit about the ‘Herivel Tip’. Both of us were surprised and delighted to find that the talk was largely about Dad’s leadership role at Bletchley Park. It was the first time that I had heard in detail of Dad’s work in words other than his own. I was also surprised to find myself and my son being identified as part of a sort of Bletchley Park ‘family’, a child and a grandchild. That must now be rather a large family!
Dad’s war work and the secrecy about it for many years afterwards had a significant impact on our family life. I think it was difficult for Dad to settle down after the excitement and creativity of the
war years, and we moved frequently, three times across the Atlantic. I never stayed in one school for more than two years, and often felt myself to be an outsider, too English in the United States, and too American in England. However, there are benefits to being an outsider, and I was very lucky to land up in some very interesting schools.
Dad was a charming person, quite the gentleman. His inclination was to enjoy life, and I remember him most with a twinkle in his eye and a subtle smile. I was occasionally startled, after he had met some slightly disreputable friend of mine, to hear of his disapproval because in their presence he was so polite and accepting. The friend would have no clue of Dad’s disapproval. However he was capable of changing his opinion later, and often did. He was always in control of himself, in my memory at least. If displeased, or perhaps a bit intoxicated, he would withdraw to his study to ‘write a letter’. We always wondered if in fact all of that time was spent writing letters, but judging by the piles of letters that remain, a lot of it was!
Dad had several personal characteristics that I believe were related to his work during the war. When something interested him, he threw himself into it. He loved music, and amassed an enormous collection of records, all of which he seemed to know quite well, and played quite often. There was a time when he took up gardening, and performed Olympian feats in transforming an unpromising rocky slope into a lush and colourful garden. He claimed that his close reading of Aku-Aku (Thor Hyerdahl’s book about the Easter Island statues) taught him how to move the ridiculously large stones. He was always curious and loved to read and learn about new ideas. When he was bed-ridden in his last months I remember him musing about a mobile of little sailing ships that floated about in the breeze above his bed, and wondering how one could tell just when they would all be in a straight line.
Dad had methodical habits. For example I remember that when leaving the house he had a system for counting off tasks that should be done on his fingers (turn out the lights, turn off the gas, lock the door, things like that). In his bachelor days after his first divorce he learned one recipe (a pot roast cooked in an electric frying pan) that I believe he served to me every time I visited during that period. It was always done in exactly the same way – quite delicious, by the way! He paid close attention to detail, for example recording even minuscule household expenses. He kept meticulous records of his tape recordings of music that he assembled into concerts he offered in a local nursing home. When calculating a tip in a restaurant, he insisted on doing long multiplication with paper and pencil, rather than estimating, which could be a bit embarrassing for his guests.
Dad’s world shifted considerably during his lifetime. He took time to change in some respects but he certainly did change eventually both in attitudes and tastes. When his children were young Dad was sometimes distant as perhaps many English fathers of his generation were. He told me in the context of my own children that he didn’t really know what to do with small children until he could read them a book. I remember being a little embarrassed by his attempts to produce appropriate Southern United States accents when reading Uncle Remus folk stories aloud to us as children. However, I believe that at times he was able to do special things with each of us children as individuals, for example birding with my sister Susanna, and fishing with me. Hiking and camping were some of the best memories that I have of family activities. I inherited a collection of Dad’s favourite photos, and several that clearly meant a lot to him were of my sister Susanna and me on a mountaintop in northern Vermont, where we used to go for summers.
I believe that Dad always considered himself to be English at heart. He applied for United States citizenship for reasons of security in his work, but he loved to return to visit his family and friends in England. It was sad that for so much of his life he did not get recognition for his work at Bletchley Park, but he told me that he felt his career had been interesting and rewarding regardless. My brother, my sister and I were enthusiastic when Joel Greenberg told us of his intention to write a book about our father. When Joel visited Nick and me in 2011 (sadly, less than a year before Nick’s death) it gave us a wonderful opportunity to revisit old memories together. We found that we had a good collection of documents to offer Joel, and were pleased by his excitement about the boxes of Dad’s papers that had been stashed in Nick’s attic, forgotten. I also had a number of photos and items of memorabilia that I was given by Dad’s third wife, Teeny. I am sure that Dad would have been very pleased to know of Joel’s project and the considerable interest in his many achievements.
Rosamond Welchman
Preface
Along with the general public, I first became aware of the story of Bletchley Park (BP) and the codebreaking activities which took place there during the Second World War when Frederick Winterbotham published his book The Ultra Secret in November 1974. I had been awarded a PhD in Numerical Mathematics by the University of Manchester several months earlier and was aware of the contributions of both Max Newman and Alan Turing to the developments in computing which had taken place there in the 1950s. I of course knew nothing of their work at Bletchley Park and was keen to find out how it had influenced their post-war work in Manchester. Much to my disappointment, Winterbotham’s book contained no technical detail. To get official approval for the book, he had restricted himself to describing how intelligence produced at BP was processed and distributed to Allied commanders in complete secrecy. In any event, he had neither access to official records nor direct knowledge of the actual techniques which produced it. British authorities continued to oppose the release of any information about the methods which were used to obtain the intelligence. Thus, subsequent books, such as Anthony Cave Brown’s Bodyguard of Lies in 1975 and Ronald Lewin’s Ultra Goes to War in 1978, also had little technical detail as those whom these authors interviewed were bound by the Official Secrets Act. R. V. Jones, who had become Assistant Director of Intelligence (Science) in the Air Ministry during the war, published his personal memoir, Most Secret War in 1978. His book told the story of the rise of scientific intelligence during the Second World War from his perspective. I eagerly purchased a copy but again was frustrated because, like Winterbotham, Jones was restricted both by what he could say about how intelligence was produced and by the fact that he was also not directly involved in the process. However, before the end of the decade, some details of the Enigma encryption machine and how it was broken were revealed in French and Polish publications.
In 1982, I came across a book published first in the United States and then in Britain, which provided a detailed description of how encrypted German communications sent over wireless networks had been intercepted by Britain’s ‘Y’ Service and subsequently read by the codebreakers at BP. Here at last was a book that I and other mathematicians, technologists and historians could get our teeth into. Unfortunately, the British and American governments didn’t feel the same way. The book, The Hut Six Story, caused quite a stir in both Britain’s Government Communications Headquarters (GCHQ) and its American counterpart, the National Security Agency (NSA). It was written by an insider who had first-hand knowledge of how the Enigma machine operated and how messages encrypted by it had been read on an industrial scale. Its author was Gordon Welchman, the man who had produced the blueprint for the BP ‘codebreaking factory’ and who had personally led the attack against the German Air Force and Army’s communications networks. With the publication of Winterbotham’s book, Welchman had felt that he was at last released from his wartime pledge of secrecy. He had always been scrupulous in protecting the secret of his wartime activities and had avoided all conversation about the war itself, other than with those in the know. This was not a position that he felt comfortable with, as he revealed to the BBC in one of several interviews which were included in their Secret War series, broadcast in 1977:
One was terrified that somehow or other one would reveal a bit of information that one had learned from an Ultra decode rather than from a newspaper … I had really had enough of
this awful responsibility by the end of the war when I was very glad to drop it, and after the war, for years and years, I didn’t even read the histories of the war because I was afraid that somehow or other I might reveal something that I had learned from Ultra.
I was certainly puzzled by Welchman’s book because earlier works had given little indication of how important his contribution had been. Yet reading The Hut Six Story and working through the technical detail provided, it seemed to me that he must have been a key figure at BP.
Welchman subsequently became an individual of some concern to both GCHQ and the NSA until his untimely death in 1985. He was interviewed several times by American Federal Agents following publication of his book and received aggressive communications from both GCHQ and NSA senior staff. Under threat of prosecution by the US Government, he was prevented from promoting his book.
He had been at BP throughout the war, arriving on 4 September 1939, the same day as the only BP veteran widely known to the general public, Alan Turing. His remarkable contribution to cryptography was achieved without any previous experience of it apart from a brief course that he attended in the spring of 1939 at the request of Alastair Denniston, the head of MI6’s cryptography section, the Government Code and Cipher School (GC&CS). He was in fact a lecturer in algebraic geometry at Sidney Sussex College, Cambridge, and had been writing a book on the subject for five years. In the early years of the Second World War he was transformed into a key figure in the triumph of BP. Within two months of his arrival, he had independently reinvented a key part of the pre-war work of Polish cryptographers and laid the foundations for Sixta, a fusion of signals intelligence and cryptography. After a further month he had made three fundamental contributions to the ultimate success of BP: he was one of the first to recognize the need for a rapid expansion of BP’s infrastructure for the decryption and analysis of intercepted Enigma traffic; he drew up an organizational plan which would enable BP to achieve such an expansion; he invented a device which would transform Turing’s design for the bombe into a workable machine. Along with Alan Turing, he had in effect developed a radically new production-orientated approach to machine cryptanalysis. BP then turned to Welchman to put his plan in place and he took on the leadership of the group which would ultimately decrypt over one million German Air Force and Army signals. In 1943 he was given responsibility for all ‘machine’ developments at BP and while he was not directly involved in its creation, the world’s first electronic computer, Colossus, was designed and built on his ‘watch’. The role also included technical liaison with American cryptographic agencies.
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