The Bletchley Park Codebreakers

HOW ULTRA SHORTENED THE WAR AND
LED TO THE BIRTH OF THE COMPUTER

EDITED BY RALPH ERSKINE
AND MICHAEL SMITH

Originally published as
Action This Day: From the Breaking of the Enigma Code to the Birth of the Modern Computer
– Bantam Press, 2001
(This edition is updated with a new chapter and additional material.)

Secret and Confidential
Prime Minister only
Hut 6 and Hut 8,
(Bletchley Park) 21st October 1941

Dear Prime Minister,

Some weeks ago you paid us the honour of a visit, and we believe that you regard our work as important. You will have seen that, thanks largely to the energy and foresight of Commander Travis, we have been well supplied with the ‘bombes’ for the breaking of the German Enigma codes. We think, however, that you ought to know that this work is being held up, and in some cases is not being done at all, principally because we cannot get sufficient staff to deal with it. Our reason for writing to you direct is that for months we have done everything that we possibly can through the normal channels, and that we despair of any early improvement without your intervention. No doubt in the long run these particular requirements will be met, but meanwhile still more precious months will have been wasted, and as our needs are continually expanding we see little hope of ever being adequately staffed.

We realize that there is a tremendous demand for labour of all kinds and that its allocation is a matter of priorities. The trouble to our mind is that as we are a very small section with numerically trivial requirements it is very difficult to bring home to the authorities finally responsible either the importance of what is done here or the urgent necessity of dealing promptly with our requests. At the same time we find it hard to believe that it is really impossible to produce quickly the additional staff
that we need, even if this meant interfering with the normal machinery of allocations.

We do not wish to burden you with a detailed list of our difficulties, but the following are the bottlenecks which are causing us the most acute anxiety.

1. Breaking of Naval Enigma (Hut 8)
Owing to shortage of staff and the overworking of his present team the Hollerith section here under Mr Freeborn has had to stop working night shifts. The effect of this is that the finding of the naval keys is being delayed at least twelve hours every day. In order to enable him to start night shifts again Freeborn needs immediately about twenty more untrained Grade III women clerks. To put himself in a really adequate position to deal with any likely demands he will want a good many more.

A further serious danger now threatening us is that some of the skilled male staff, both with the British Tabulating Company at Letchworth and in Freeborn’s section here, who have so far been exempt from military service, are now liable to be called up.

2. Military and Air Force Enigma (Hut 6)
We are intercepting quite a substantial proportion of wireless traffic in the Middle East which cannot be picked up by our intercepting stations here. This contains among other things a good deal of new ‘Light Blue’ intelligence. Owing to shortage of trained typists, however, and the fatigue of our present decoding staff, we cannot get all this traffic decoded. This has been the state of affairs since May. Yet all that we need to put matters right is about twenty trained typists.

3. Bombe testing. Hut 6 and Hut 8
In July we were promised that the testing of the ‘stories’ produced by the bombes would be taken over by the WRNS in the bombe hut and that sufficient WRNS would be provided for this purpose. It is now late in October and nothing has been done. We do not wish to stress this so strongly as the two preceding points, because it has not actually delayed us in delivering the goods. It has, however, meant that staff in Huts 6 and 8 who are needed for other jobs have had to do the testing themselves. We cannot help feeling that with a Service matter of this kind it should have been possible to detail a body of WRNS for this purpose, if sufficiently urgent instructions had been sent to the right quarters.

4. Apart altogether from staff matters, there are a number of other directions in which it seems to us that we have met with unnecessary impediments. It would take too long to set these out in full, and we realize that some of the matters involved are controversial. The cumulative effect, however, has been to drive us to the conviction that the importance of the work is not being impressed with sufficient force upon those outside authorities with whom we have to deal.

We have written this letter entirely on our own initiative. We do not know who or what is responsible for our difficulties, and most emphatically we do not want to be taken as criticizing Commander Travis who has all along done his utmost to help us in every possible way. But if we are to do our job as well as it could and should be done it is absolutely vital that our wants, small as they are, should be promptly attended to. We have felt that we should be failing in our duty if we did not draw your attention to the facts and to the effects which they are having and must continue to have on our work, unless immediate action is taken.

A. M. Turing
W. G. Welchman
C H O’D Alexander
P. S. Milner-Barry

We are, Sir, Your obedient servants,

Secret
In a locked box
Gen. Ismay

Make sure they have all they want on extreme priority and report to me that this has been done.

WSC

22.x

Hugh Alexander
joined Hut 6 in February 1940. He became deputy head of Hut 8 in March 1941, and its head during the autumn of 1942. He later worked on Japanese naval codes and cipher machines.

Gustave Bertrand
was a member of French military intelligence, in its cryptology section. He supplied vital documents on Enigma to Polish intelligence and the Government Code and Cypher School (GC&CS).

Frank Birch
joined the German naval section at Bletchley Park in September 1939, and later became the head of the naval section.

Joshua (Josh) Cooper
joined GC&CS in October 1925 to specialize in Russian codes and ciphers, later becoming head of the air section.

Alastair Denniston
was the operational head of GC&CS from its establishment until February 1942. He was then appointed the Deputy Director (Civil) (DD(C)) in charge of the section responsible for diplomatic and commercial codebreaking. He retired in 1945.

Thomas (Tommy) Flowers
was the engineer at the Post Office Research Station who designed Colossus.

Hugh Foss
joined GC&CS in December 1924. He devised a method to solve non-plugboard Enigma in the late 1920s, and was head of the Japanese naval section in 1942 and 1943.

William Friedman
was the founder of the US Army Signal Intelligence Service (SIS), and its head until 1941. He was appointed the Director of Communications Research in November 1942.

Harold (Doc) Keen
was an engineer at the British Tabulating Machine Company, which made the British bombe. He was responsible for the detailed design of the bombes.

Dillwyn (Dilly) Knox
was the chief cryptographer (cryptanalyst) at GC&CS. He was severely ill from 1941 onwards, and died in February 1943. He specialized in breaking non-plugboard versions of Enigma.

Stewart Menzies (‘C’)
became the head of MI6 in 1939 and, as such, was also the Director of GC&CS (Director General from March 1944).

Stuart Milner-Barry
joined Hut 6 in early 1940, becoming its head in September 1943.

Maxwell (Max) Newman
was the head of a GC&CS section known as ‘the Newmanry’, which attacked the Tunny cipher machine.

Marian Rejewski
was the Polish cryptanalyst who first solved plugboard Enigma, in 1932.

Telford Taylor
was a lawyer who joined US Army Intelligence in 1942. He made an extended visit to GC&CS in April 1943, and later worked in Hut 3.

John Tiltman
was the head of the military wing at Bletchley Park, and GC&CS’s top cryptanalyst on non-machine ciphers. He was appointed chief cryptographer in 1944.

Alan Turing
joined GC&CS in September 1939, and was head of Hut 8 until autumn 1942. He also worked on Tunny.

Edward Travis
was a deputy to Alastair Denniston until February 1942, when he was appointed Deputy Director (Services) (DD(S)) in charge of the services’ side of GC&CS. He became the Director of GC&CS in March 1944 (when Menzies’s title was changed).

Gordon Welchman
was the head of Hut 6 from its establishment until about the autumn of 1943, when he became the Assistant Director, Mechanicisation.