Security at Bletchley Park

One way in which British Sigint during the Second World War anticipated the way many people work today was in having not just to find ways to provide physical security for the vast quantities of sensitive data being created, but in persuading large numbers of workers with no instinctive or habitual feeling for secrecy to protect the material they dealt with. I've written about the way in which infiltration by communists or communist sympathisers was handled – but how did Bletchley Park ensure that its site remained secure and persuade the ordinary people who made up its staff not to talk about their work, to the extent that few said anything about their involvement with Sigint for thirty years after the war came to an end? 

The initial approach to security at Bletchley Park was to surrounded it with secrecy. The name "Bletchley Park" was not to be mentioned: instead it was referred to as "Station X"; staff were forbidden to reveal the location, even to their families. However staff had to billeted and it was impossible to prevent it being known that Bletchley Park had been taken over by the Government. SIS came up with a cover story – that Bletchley Park was involved with the Air Defence of London – which it was thought would satisfy local inquisitiveness, but this cover story was not used when Bletchley Park was temporarily occupied in 1938 during the Munich Crisis and staff were told what their cover was until after the site was occupied in August 1939. The initial staff scattered about the neighbourhood – members of the Foreign Office, professors of Modern Languages, historians and mathematicians – had no obvious qualification for air defence: it is hard to believe that any one of them could have answered the simplest question if asked.

After SIS had mostly returned to London, the GC&CS leadership decided to change the cover story and to refer to the organisation at Bletchley as "Government Communications Headquarters", a name that was vaguer and potentially covered a broader field than Air Defence. But again the first staff of GC&CS knew about the new name was when in October 1939 they found it displayed on a large white painted signboard at the entrance gates – a sign which was subsequently removed.

The idea of keeping secret where staff were broke down almost at once. People had lives to live outside work and consequently had to have an address and, anyway, after a time some moved their families into houses nearby. At first an accommodation address had been provided: Room 47, Foreign Office; but as numbers grew the amount of work for the Foreign Office became too much, the last straw, allegedly, was when a motor cycle was delivered there. It was only in 1942 when a Bletchley PO Box Number was arranged, mainly for those whose billet address was uncertain, and a London Box Number was arranged which could be used for letters sent abroad (on which the Bletchley address was forbidden).

(There were fewer problems with the Y Stations: there was no question of concealing their presence or their function. But it was common knowledge that WT was used by the Services and the normal measures common to any Service station to prevent unauthorised visitors were satisfactory, though care was needed to prevent senior officers from entering without authorisation. Most commanding officers adopted some cover story for local use, for example that they were relaying weather reports.)

At Bletchley, physical security developed slowly. A solid iron ring fence was put up in the spring of 1940, but as GC&CS grew the fence had to be considerably lengthened and chain wire netting was substituted for the ironwork. There were only two official entrances. The most that can be said for the fencing was that it offered a sort of deterrent: it offered virtually no obstacle to a determined person and was neither lit nor patrolled at night. (During a Home Guard exercise early in 1943 the attackers removed a complete section under cover of darkness with no more formidable weapon than a spanner, and so attacked the defenders, somewhat unsportingly it was felt by the defenders, from the rear.) But it kept out casual intruders and ridiculously insecure as it probably was, it served its purpose during the war.

Every member of GC&CS and certain regular visitors were issued with standard passes. Theoretically passes were examined at the entrance gates but in practice they were simply waved at the gate guards by staff on their way in. There were two kinds of guard on the gates, Military Police, with armed sentries, and unarmed Foreign Office Security Police, recruited from pensioners in the Metropolitan Police. They got to recognise GC&CS staff and were probably the best security GC&CS had against infiltration. The Military Police boarded the incoming coaches and stopped all cars so that passes could be shown. Staff without passes were detained until recognised or claimed by their sections and these cases were reported to the Administration. Of course there were plenty of cases of people who had forgotten passes coming in at busy times and dodging the guard, of passes being handed through the fence out of sight of the gate by someone who had already entered, and of passes lent by someone coming off duty on foot to a pass-less colleague still outside the gate. In fact the number of forgotten passes each morning was considerable and steps had to be taken to make getting those staff into work as tiresome as possible, both to the individual and to their section, which had to send somebody to the guard hut to vouch for their identity. The alternative would have been to refuse entry altogether, which as there was no public transport would have left most individuals who were billeted outside Bletchley with no means of getting back to their billet as well as the loss of a day's work. There were relatively few cases of passes being lost: a fine was imposed to pay for a replacement. Like the fence, the pass system was adequate for the time and place, though not really offering much in the way security.

Temporary passes were issued to craftsmen and others who had business within the perimeter by BP administration. They either remained in sight or were escorted by the Military Police. Visiting military officers also received temporary passes and had to be vouched for by one of a small number of authorised staff from GC&CS. They were also escorted while on site. Further limitations were put upon the entry to work areas both by visitors and by staff from other sections, according to their "need to know".

Standing Orders provided that no room was to be left unoccupied unless all papers had been locked away. At times, whole rooms had to be locked and regarded as "cupboard rooms". The Foreign Office police patrolled buildings each night and all open windows or unsecured papers were reported, papers being kept by the police until the next morning. A "security officer" was appointed in each section to coordinate this within the section but there were many examples of carelessness among staff unaccustomed to this sort of behaviour. It was made more difficult anyway because the cupboards supplied were of poor quality and many of their doors opened enough when locked for a hand to be inserted without difficulty and the fastenings could be broken away by a sharp pull. It made all the fuss made about securing classified material seem futile.

Paper was by far the greatest security issue for GC&CS. The quantity was enormous. Forty or fifty thousand enemy signals entered GC&CS every day and the Cypher Office was handling between two and three million cypher groups (a further twenty or thirty thousand messages between BP and UK authorities) a week. The floors of the signals and deciphering rooms were covered in tape all of which had a gummed underside which stuck to shoes on a damp day. Each section generated formal papers of every kind and received large quantities as well. Most was carefully handled and the registration process prevented even more problems. But there was a lot of unrecorded paperwork as well, and the acute national shortage of paper meant that paper had to be kept for recycling rather than be simply destroyed by burning.

The routine for dealing with confidential waste was to have it collected once a day, sacked, tied up, locked up and taken once a week to a local paper-mill where it was tipped into bleaching vets under the supervision of the GC&CS security officer who had taken it there. This process worked reasonably well. The only difficulties came from GC&CS staff. They produced three kinds of waste – white paper, coloured paper (e.g. carbon paper, brown paper, cardboard boxes) and "hard core" which included almost every conceivable object except paper. The paper mills insisted that white paper should be separated from coloured paper as only white paper waste could produce pulp clean enough for new paper (coloured pulp was used for cardboard). Any hard object in the waste was liable to break the machinery, and glass in particular was dangerous to the workers. Three containers had to be supplied to every room for the three different kinds of waste. Paper waste of both grades was treated as secret while hard core was dealt with at the local council tip. The problem was to persuading staff to use the proper container and from a security point of view the danger lay in the hard core bins. Each member of staff was told how things worked on arrival in their section, was given written instructions, was again specifically reminded at a Security lecture, but carelessness remained an outstanding feature.

Physical security measures at GC&CS were probably not any worse than procedures in the Ministries, except that the grounds in which the offices stood were more vulnerable than a London building. The title "Government Communications Headquarters" worked well enough, though this disguise wore rather thin when the Army ordered shoulder flashes to be added to uniforms and the Bletchley area was thronged by soldiers labelled "Royal Corps of Signals" and "Intelligence Corps" – from a GC&CS point of view an unfortunate association of ideas. But in general GC&CS consistently pursued this policy of being low key, avoiding appearance before local tribunals or in any matter that might engage the attention of the Press or public. The cover stories probably increased rather than reduced curiosity. By far the best protection for GC&CS staff was simply to say that they couldn't talk about their work: to appear, as Churchill remarked of them during his visit 'innocent though engaged in a sinister occupation'.

Every new entrant (civilian or service, at Bletchley or at stations) read and signed an extract from the Official Secrets Act as did everybody leaving in a formal "signing off" process. In GC&CS after the signing of the Official Secrets Act staff were warned that no mention of the nature of the work outside the organisation was allowed, and this warning was included in the Standing Orders issued to them. Further security instruction was left to Section Heads to handle and this system continued until the beginning of 1942 when all security-related matters were centralised when Henry Hayward became Senior Security Officer for GC&CS.

Being "war entry" himself, he realised that suddenly exposing new entrants to highly secret information was an unusual experience and potentially a source of acute anxiety to some, while for others security rules would be no more important than rationing rules or petrol restrictions, which most people were prepared to dodge on the quiet. His solution was to ensure that Security became part of everybody's work rather than a bolt-on, and to do so, he rethought the way that new entrants were trained in security.

His plan was to give a simple lecture to every new entrant a few days after they arrived, followed by the signing of a solemn declaration which listed the main points of the lecture. This paper dealt in the main with the best answers to be given to ordinary everyday questions from acquaintances. It was handed out to be read and signed after the lecture, returned to the Directorate and, as it was a confidential document, its arrival or non-arrival until chased offered a clue to the reliability of the individual. This did not take the place of signing the Official Secrets Act, but supplemented it. Each batch of recruits – the intake was at first about 30 arriving every Monday morning – attended the lecture some three or four days after being signed on. They were divided into three categories according to the "need to know" their work attracted: those engaged in Sigint proper; those employed in support areas such as the Communications Section where there was no need for them to hear about the methodology of Sigint; and staff such as messengers, maintenance and catering, who might enter offices at times and who would certainly overhear other people talking about classified subjects. The lecture was varied according to the audience, the last category being especially warned against inquisitiveness, talking outside the perimeter of anything they saw (for example machinery) or anything they heard, but were otherwise given no information about the purpose of the organisation. The same lecture was given to the WRNS at Stanmore and Eastcote. Hayward visited these stations at longer intervals and audiences varied from about 100 up to 250.

His lecture always covered the following points:

1) Explanation of the provisions of the Official Secrets Act.

2) The Purpose of GC&CS.

3) The effect of its work on operations.

4) How it might be lost and the effect of doing so.

5) 'There is only one way of keeping a secret, and that is to tell it to nobody' not even to the nearest and dearest or others in the same uniform.

6) Behaviour: 'Do not surround yourself with mystery and avoid arousing curiosity' and how to answer casual or not so casual questions.

7) Not to write indiscreet letters.

8) The principle of need to know. 'Secrets which you do not need to know are an unnecessary burden and someone else's secret is never quite so secret as one's own', and how this led to the principle that members of one section should not discuss their work with members of another except when necessary.

9) The honour of the Service.

(Before anyone asks, I do not know what "The honour of the Service" covered.)

Hayward gained a further insight into the sort of issues staff needed to be warned about as all security breaches were reported to him. Most cases fell into one of three main categories: victims of the confidence trick – senior officers saying 'I know all about your work as I was an intelligence officer in the last war' or parents saying 'You can surely trust me'; people who deliberately attracted attention ("men of mystery"); and what he described as "chatterboxes and letter writers". Of these the last category was by far the largest and the most easily dealt with.

Staff were told that it was their duty, however unpleasant, to report security breaches at once and Hayward ensured that incidents were handles in such a way as to minimize any personal animosities. In his words: "It was made to appear rather more a question of helping a weaker vessel than reprimanding a naughty child."

Hayward arranged periodically for a week or so's censorship on all letters leaving or entering the area in which GC&CS staff were living. This produced on each occasion a small crop of letters which were returned to GC&CS for action. No really serious security breach was discovered and all were easily dealt with, but it demonstrated the need to explain in simple language what constituted careless talk and what was meant by security.

American Air Force officers regularly invited WRNS and other young women employees to their dances. Unfortunately the drinks served tended to be both stronger and more plentiful than most of their guests were accustomed to. The presence of women in Naval uniform in the heart of the country was intriguing and led to a degree of innocent questioning. So many cases of indiscreet talk occurred that GC&CS felt obliged to ask the WRNS not to allow their personnel to visit certain American stations. The problem was passed on to the US Army Sigint authorities in the UK, who sorted things out at their end. The security problem was perceived to be greater because of the likelihood that some at least of these officers might fall into enemy hands.

There were some cases of mental breakdown. Fortunately in an early case the patient, by that time in a nursing home, wrote to a colleague about work matters. It was immediately appreciated that a letter like this could be sent to anyone. MI5 was called in and arranged for doctors and nurses to be interviewed and letters censored. This became a standard procedure.

Security breaches during the Second World War were relatively infrequent and easily dealt with.  The idea that maintaining secrecy was an integral part of everybody's job became embedded within the organisation, and many of the practices begun there continued after the war, and indeed to the present day.