Alastair Denniston

by Alastair Denniston- Code-breaking From Room 40 to Berkeley Street

  AGD had organised a short course in London from 3 to 6 January 1939 which was attended by M.P. Charlesworth, P.E. Charvet, D.W. Lucas, L.P. Wilkinson, A.M. Turing, H.M. Last, G.R. Driver, T.F. Higham and C.H. Roberts. Further recruits were put through a course from 20 to 23 March and from 27 to 30 March 1939. They were all earmarked for specific sections at BP on mobilisation and AGD gave a short historical sketch at the beginning of each course.

  As more staff began to arrive, the logistical problems which had been identified during the ‘dress rehearsal’ the previous year, had still not been resolved. AGD wrote to Menzies on 12 September 1939:

  My dear Menzies,

  I am sending you herewith a memorandum which Travis and I have drafted as I had the Admiral’s permission to discuss administrative details with you. The whole question will shortly become so acute that it will have to be laid before him for decision, but in the meantime I wish to make you fully aware of the present position and of future requirements.

  In addition to the present policy which has forced G.C. and C.S. into disintegration which I have always held to lead to a real loss of efficiency, I take the opportunity of repeating to you the discontent, in the staff of G.C. and C.S. which is now becoming increasingly vocal, with the actual conditions of work.

  The contention is that G.C. and C.S., a Civil Service organisation, was moved out of London by orders of the Admiral and not by orders of the Foreign Office (our administrative head) and that therefore the G.C. and C.S. must receive equality of treatment with S.I.S. who were also moved by the Admiral’s order.

  Travis and myself and the Senior Assistants now occupy fairly senior positions in the Service and many of our recruits are men of considerable distinction and it is definitely felt that in the allocation of accommodation such facts should be taken into account. It appears to me improper to invite such as these to try to do work requiring a high degree of concentration in overcrowded rooms.

  Again the question of billeting, which Captain Ridley has carried out with such tact in the face of difficulty, has forced the staff to live many miles from their work and the question of transport is involved. It is felt that official cars can be made available for members of S.I.S. but G.C. and C.S. has had to raise a force of volunteers from among its own members and ask them to give their time and their cars to help their colleagues. In fine weather it is hard for a man who has had a heavy day to forego his leisure for this – in the dark evenings to come it will be even harder. If there are not sufficient official cars to do this duty would it not be possible to engage the W.V.S. to deal with the transport of the staff between office and billets?

  I have done a great deal and will do all I can to maintain a spirit of cooperation. But there is a real spirit of discontent growing among my colleagues. I have congratulated them on the good work that is being done under very trying conditions and the natural reply is improve our conditions and you will get more results.

  The few days that have elapsed since the outbreak of war are sufficient to show that we may hope very soon to contribute intelligence of a definite military value to the Fighting Services. If however we are to function efficiently we must be reasonably housed. These are the main considerations.

  Cooperation between the three Service Sections is essential.

  All sections should be in close proximity to the Teleprinter Room, for a great part of the raw material used by all sections is transmitted from the Y stations and some of the Cable offices. It should be remembered that The Foreign Office agreed to spend £4000 a month to ensure this rapid means of communication for its own ultimate advantage.

  I have always viewed with very grave concern the fact that the Military Section has been moved to the garden to make room for a mess which is used for one hour per day, and the Air Section is also being moved away from the teleprinters to make way for a registry. The Air Section should be right on top of the teleprinters and the Naval Section, with whom it may have to confer urgently and frequently.

  The Section working on the machine problem is in No. 3 Cottage and development there is becoming much more hopeful and here again they require very close cooperation with the section with whom they are working. The Diplomatic and Commercial Sections are in Elmers3 School. Although these sections are called Diplomatic certain of them require collaboration with the Service sections and produce matter of military importance. Twenty minutes spent walking backwards and forwards on a dark winter’s afternoon is not going to make for efficiency.

  Further, the Naval Section is now grossly overcrowded and we have to remember that we have added to our staff volunteers of very considerable standing and the research work they will undertake is of extreme national importance and one which calls for some degree of comfort in their surroundings in order to get the best out of them.

  It must be remembered that the three weeks we have been here have been remarkably fine and the walking about has been pleasant. With dark afternoons and evenings and cold conditions, people will hesitate to walk out in the open considerable distances to confer with colleagues. In our overcrowded state the use of the telephone, never satisfactory, is impossible.

  It seems that there is not room to house SIS and GC&CS in Bletchley Park efficiently. The only alternative therefore is to separate. It appears to be most difficult to move the teleprinters and provide lines for them, and it therefore remains to examine whether alternative accommodation can be found for some or all sections of SIS.4

  On 14 September AGD received a reply from Sinclair:

  Colonel Menzies has reported to me the results of his interview with yourself and Travis, yesterday. I understand that some temporary arrangement of erecting further huts is contemplated, which it seems to me will not meet the case.

  Now that the dug-out in the basement of Broadway Buildings is approaching completion, which will accommodate up to 500 people, is there any reason why the Diplomatic Section and the Commercial Section (2nd Wave) should not return to Broadway Buildings, so that the situation at the War Station, which I understand you describe as unbearable, may be relieved?

  If you concur that this is desirable, in the interests of efficiency, arrangements should be made for the Second Wave to return to Broadway Buildings as soon as conveniently possible. If, however, you do not concur, I shall require from you the fullest and most convincing reasons as to why this should not be done.

  Pending an immediate reply from you, I shall not give orders in regard to this matter. I understand that, in any case, the teleprinters will not be required to be transferred from the War Station, as I have gone very carefully into this matter, and I find that the material can be obtained direct from the Censors and Cable & Wireless.

  Sinclair wrote again to AGD the following day after consulting with the DNI:

  It is quite apparent to me that the Commercial Section of the G.C. & C.S. will require large additions to the staff, in order to enable it to cope with the work with which it is confronted.

  As it is quite impossible to accommodate such individuals at Bletchley, arrangements should be made for the early return of the whole of this Section to London, in order that the work may be properly dealt with.

  AGD had always believed that all of GC&CS should remain at BP and he made his case most strenuously in a note to Sinclair on 16 September:

  In my private letter to Menzies I did not describe the position as unbearable and I was careful to raise in the annex only matters affecting the efficiency of the Service Sections. The transfer of the Diplomatic Sections to Broadway would not affect this problem, nor would it be possible to separate the Service Sections by housing one of them in the School.

  Although I have no doubt that our personal safety would not suffer by return to Broadway, and personally I should much prefer to be near my home, I do feel that that the possibility of hours spent on a crowded public shelter and the time wasted in putting work away and getting it out again would render any real work by the Diplomatic and Commercial Sections quite impos
sible.

  Suburban rail and road transport is difficult at present and it may become considerably worse, in which case it will be extremely difficult to put in a full day’s work.

  The work of the G.C. & C.S. as a whole is bound to suffer if we are split into two sections e.g. as a first step in the coordination of the scrutiny of the mass of German traffic from all sources I have established under my own control a central German Coordination Section and would be difficult to determine whether this should be in Broadway or Bletchley.

  My submission therefore is that the whole of the G.C. & C.S. including the Commercial Section should remain at Bletchley.

  Captain Ridley is now arranging to remove the private furniture from the school and to have the lighting and heating put in order, when this has been done the working conditions in the school will be greatly improved. The large schoolroom is at present practically empty and I propose to transfer the Commercial Section there; it will accommodate about 30. If and when it were found necessary to expand this Section further, it should be possible to transfer the staff engaged on decoding legible commercial codes to a place near M.E.W.

  There has been no question of the erection of huts for the Diplomatic and Commercial Sections.

  There is now under consideration a plan for the erection of huts just outside the grounds of BP to house the Service Sections including their necessary expansion, thereby facilitating the necessary expansion of various sections of SIS. It would be necessary to connect these huts with the Teleprinter Room by pneumatic tube.

  Finally I shall be personally very greatly relieved when these administrative difficulties are settled as I am most anxious to take my share of the work on the increasing numbers of cryptographic problems confronting us.

  Crucially, for the ultimate success of BP, AGD won the day and by 29 September 1939, the huts were under construction.

  AGD had kept in contact with Bertrand and in September, a party of French intelligence officers including Bertrand and Henri Braquenie visited BP. Knox was tasked with looking after them, and true to form, was soon writing to AGD about the matter:

  My dear Denniston,

  I think it is time we settled on one or two points of general principle.

  Entertainment. It has been a great pleasure to me, though somewhat testing to my knowledge of French, to bear-lead Captain B. from 8 a.m. to 10 p.m. I have taken the line, though he offered to pay generously, that entertainment is une affaire de bureau: that is, from my angle, that I should get a billeting allowance from you or Ridley and that you or he should deal with the French. Drinks and transport other than that to or from the Office (for which I get an allowance) I treat as private liability. I trust that this view has been right and will continue, since I don’t like making special charges.

  Machinery material and Statistics (Liaison).

  We can also continue to cooperate on the reconstruction of the two Italian codes. As yet, there has been no discussion on Italian naval and military cyphers and on this question I should like to receive orders in view of the fact (a) that I suspect that the Italian Navy is being worked in another branch in Paris, and (b) that the Foreign Office considered that cooperation on the Italian military telegrams between Spain and Rome was, at that time, undesirable. I assume that Commander Travis handles any questions of finance arising from price of machinery or material (paper for ‘Netz (Filets)’ or wood or cardboard for rods).

  Statistics. (Up to present). I take it that we have been making statistics at our own expense and Travis charges the material to the French.

  As regards labour, then we should keep a check, if at all, only on time spent in reduplication which may be considerable as we may have to mark, punch and cut holes twice. It is easy to keep a check on time spent in this way. The French would get their stuff at about a quarter of what we would pay. I don’t see how they can actively help as they are a very long time behind and we should have to fly over heavy machines and quantities of paper, or, if they did help, risk everything being out of gauge.

  At present I am talking only of Jeffrey’s ‘Netz (filets)’, (reduplication will begin in a few days), where I made some rather conditional offers, without, of course, mentioning finance. I think, however, we could only charge here for reduplication.

  In the matter of sex-statistics there is no precise arrangement as yet either as to methods of as to finance, since all progress has been made since B’s departure (see my letter of the 26th Sept.). If my estimate of my new machine with Travis’s and H.-M’s improvements is correct we could either:

  handle the whole affair on a fifty-fifty basis, or

  Charge for necessary reduplications as suggested for Jeffrey’s ‘Netz (Filets)’.

  If you can give any definite ruling as to whether:

  We make no charge for labour.

  We charge only for extra labour of reduplication.

  We charge fifty-fifty.

  I will institute a simple system of checking if necessary.5

  On 4 September, two Cambridge mathematicians who were on AGD’s list arrived at BP and would prove to be fundamental to its ultimate success; Alan Turing, aged 27, from Kings College, and Gordon Welchman, aged 33, from Sydney Sussex. Both were greeted separately by AGD and then told to report to Knox, who had moved along with his small team into one of three cottages in the stableyard behind the house. Knox already knew Turing, as he had done some part-time work for GC&CS in 1938. Welchman had attended the courses in London in March but would later write that he had no recollection of meeting Knox at that time. While Turing remained in ‘The Cottage’ with Knox, Welchman was moved to the former Elmers School. It lay outside of the grounds of BP and had been acquired by GC&CS to provide additional office accommodation. While primarily tasked with analysing specific information included in every Enigma encrypted message,6 Welchman had other ideas forming in his mind.

  When AGD and Edward Travis came together in 1919 in the newlyformed GC&CS, AGD had taken responsibility for cipher breaking, and Travis for cipher security under him. This separation of roles continued in the early days at BP, even though the cipher ‘Construction Section’ was now based in Oxford. Travis had been made responsible for the Service Sections of GC&CS in 1938. AGD was very busy coping with the administrative problems arising from the move to Bletchley and the subsequent expansion and as a result did not spend much time out of his office. Travis did make it a habit to get out of the office to see the work on the ground and talk to the staff. So Travis was in effect responsible for the ‘Enigma Section’, though Dilly often continued to write straight to AGD. Travis also had a direct interest in the security of Enigma as at this time he was concerned with the deployment in the British Services of the Typex machine, which was designed on very similar lines.

  Working away in Elmers School with another member of Knox’s team, Tony Kendrick, Welchman was seeing something in the intercepted traffic which had escaped others. As he later recalled:

  Previously I suppose I had absorbed the common view that Cryptanalysis was a matter of dealing with individual messages of solving intricate puzzles and of working in a secluded back room, with little contact with the outside world. As I studied the first collection of decodes, however, I began to see, somewhat dimly, that I was involved in something very different. We were dealing with an entire communications system that would serve the needs of the German ground and air forces. The call signs came alive as representing elements of those forces, whose commanders at various echelons would have to send messages to each other. The use of different keys7 for different purposes, which was known to be the reason for the discriminants, suggested different command structures for the various aspects of military operations.8

  While analysis of the enemy’s wireless traffic was undertaken both by Room 40 and MI1(b) during WW1, what no one at BP seemed to have recognised was that a considerable amount of intelligence could be obtained from intercepted German messages by analysing the traffic as a whole. Welchman drew up a comp
rehensive plan calling for the close coordination of radio interception, analysis of the intercepted traffic, breaking Enigma keys, decrypting messages on the broken keys and extracting intelligence from the decrypts. It is likely that as Travis was a more visible presence at BP in the early days, Welchman decided to present his plan to him and he immediately saw the urgent need to act on it. Welchman convinced Travis that a large scaling-up of the effort would be needed when the methods of breaking Enigma, outlined in his plan, produced results. He was in effect proposing a system of mass production which was completely at odds with the approach taken by Knox. In his world, the various tasks of decryption, translation and writing the resulting out-going message were all performed essentially by one cryptanalyst. Welchman and now Travis realised that this approach would simply not be able to handle the volumes of intercepted traffic envisaged. It would have to be replaced by a clear division of labour amongst a team of experts. Travis won AGD over to the idea and then remarkably, persuaded Whitehall to back this gamble, even though not one German Enigma message had ever been broken in the UK either before or since the war began.

  Welchman’s plan was soon the subject of discussion around BP and not surprisingly, Knox was not happy with it. His view was that research was all important and that ‘Bletchley Park should be a cryptographical bureau supplying its results straight and unadorned to Intelligence Sections at the various Ministries. At present we are encumbered with “Intelligence Officers” who maul and conceal our results, yet make no effort to check up on their arbitrary corrections.’