Women of Intelligence: Winning the Second World War with Air Photos (10 page)

RAF Medmenham was the home of Second-Phase interpretation, keeping an up-to-date record of all enemy movements, activities and new constructions relating to land, sea and air forces. This formed a most detailed, comprehensive record of what the enemy was engaged in from day to day. With this knowledge, it was possible not just to predict, but to know for certain what the next enemy move would be, giving an opportunity for an Allied countermeasure to be put into operation. The Third-Phase sections, around thirty in total and specialist in nature, were also housed at RAF Medmenham. Each was designated by a letter of the alphabet and concerned with one specific aspect of enemy activity.

Comparing photographs of an area or activity with others taken on previous cover was the only way of establishing if any changes had taken place. Comparative cover was one of the most useful tools the PI could use, for without comparison over time there was no way of knowing what was, or was not, normal. An air photograph of an enemy airfield might show a single track leading to a runway for light passenger aircraft. One month later the track could have become a well-surfaced road with several heavy transport planes visible among different types of aircraft, indicating that something was happening: comparative cover would show the change in use and purpose. It was then the responsibility of the PI to find the answers to the questions and report on them. Captain Dirk Bogarde summed up the fascination that PIs had for their work:

You needed observation, an eye for detail and memory. I loved the detail, the intense concentration, the working out of problems, the searching for clues, and above all, the memorising.
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Intervals between flying photographic sorties could range from a matter of hours in a rapidly changing situation, to a regular ‘watching brief’ of days or weeks. When an operation was being planned, one of the first orders would be for a significant increase in photographic cover of the area concerned, which would form a major part of the intelligence gathering and influence the planning and decision-making process. Even when intelligence came from other sources, for instance by electronic or human means, it invariably had to be verified with photographic cover. The plans for virtually every wartime operation included the words: ‘The photographs show …’

Maps and charts are fundamental to every armed force activity on land, sea or air, and constitute one of the earliest forms of intelligence. This part of the course put the mathematical skills of the students to the test. Dorothy Colles passed her PI course in 1941 despite a few doubts:

On the last course all the WAAFs and half the RAFs failed. I have looked at all the manuals and am overwhelmed - not that one does it in a few weeks, but that one does it at all! I can see some most involved mathematical calculations ahead of me!
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By the afternoon of Diana Byron’s first day, the students were immersed in learning the standard procedures of basic scaling, recognition, identification and measurement that all PIs follow when looking at an air photograph. On each desk was set out the ‘tools of the trade’: a simple, pocket-sized stereoscope, which looked like a pair of spectacles mounted on a fold-up stand, a magnifier with graticules for measuring, photogrammetric tables and sets of trigonometry tables, a slide rule and an anglepoise lamp to provide a strong and adjustable source of light.

The scale of an air photograph had to be determined in order to identify objects correctly by size and recognition. The process involved the accurate measurement of the size of an object relative to its size on the ground; sometimes the object was little more than a speck seen on a photograph taken at a height of 30,000ft. Before the invention of the pocket calculator, the slide rule was the most commonly used calculation tool in science and engineering. Looking like an overlarge folded-up ruler, it was used to multiply and divide and calculate functions such as roots, logarithms and trigonometry. Hazel Furney and Sarah Churchill were together on their course at Nuneham:

Five of us shared a room. I liked Sarah very much – she had an awful inferiority complex and was terrified of letting the family down. One day we all did a test report on an aerial photograph of which she had got the scale wrong, and then she asked me why she had got so much of her interpreting wrong. When I realised and told her what she had done, she disappeared. Later I found her sobbing her heart out on her bed, convinced she had failed. Needless to say, she wasn’t sent away.
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Sarah’s abilities with a slide rule improved and she passed the course, although she still lacked confidence in her mathematical capabilities. So she devised an ingenious solution to her problem:

When faced with the complexities of setting a slide-rule, I would tiptoe downstairs and ask a friend, one of the model makers, to do it for me. In fact, I got two slide rules, so that I would not have to change the setting if the photographic sorties used cameras with different focal lengths. David would set them both, once I knew the areas I was working on, and I would then carry them gingerly back upstairs.
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Ursula Powys-Lybbe, who had been a professional photographer before the war, enjoyed mastering scaling and the slide rule:

Generally all that had to be done was to pull out the map sheet of the area covered by the photographs, make a note of its scale (1:25,000 for example), multiply that by the distance between two points measured on the map, and divide that total by the distance between the same two points seen on the photograph, and the answer is the scale of the photographs. It was then possible to arrive at the measurement, say, of the wingspan of an aeroplane in feet … I can say with pride that it took nearly a week for me to be able to multiply and divide with the help of the slide rule, and I was so gratified that I wrote a ‘Child’s Guide in the Use of the Slide Rule (Simplified Version) with Illustrations’, to make it easier for limited persons like myself.
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Like repeating a mantra, students muttered ‘size, shape, shadow, tone and associated features’ to remind themselves of the five elements of interpreting an air photograph. Colour film was rarely used in air photography as black-and-white prints revealed varying tones far better, making identification easier even when an object was camouflaged. As familiar objects become unfamiliar and unrecognisable when seen from above due to the loss of normal perspective, many hours were spent learning to recognise the shape of every feature of a landscape shown on an air photograph. The silhouettes of military and naval equipment were committed to memory from recognition charts and manuals.

In binocular vision, each eye records an image and the brain fuses those two separate images, resulting in vision with depth, which we accept as normal. An ordinary photograph merely provides a flat two-dimensional representation, but the Victorian novelty of stereoscopy could change that into a three-dimensional picture. Stereoscopy had proved its value to military intelligence in the First World War and now, in the second, stereoscopy teamed with superior measuring devices allowed minute objects on very small-scale photography to be measured and identified. When a reconnaissance pilot flew over a target area, the cameras were automatically set to expose the film at calculated intervals, causing each frame to overlap its successor by 60 per cent. When the PI adjusted the two overlapping prints, termed a ‘stereo-pair’, under a stereoscope, the two separate images ‘fused’ and the three-dimensional effect of normal vision was reproduced. Using two images, rather than one, greatly increased the knowledge that could be gained from an air photograph. All three dimensions of height, width and depth could be accurately measured, making recognition of an object possible. Stereoscopy also enabled identification of objects hidden on a two-dimensional image: for example, vehicles parked under camouflage were likely to be ‘invisible’ on a flat photograph, but were revealed under a stereoscope where the 3D effect showed up the depth and the varying tones.

The students spent some time away from their desks discovering the practical side of PI. Jane Cameron recorded a visit:

We went to Farnborough today by bus to see the shot-down and reconstructed German aircraft and I do so wish aircraft meant a little more to me. Ships are different – ships are like people, gifted with an actual personality and with an infinite capacity to please the eye and mind, but aircraft – no. They are like motor cars, humdrum, soulless machines in which to go from A to B, and no more. Sometimes, in the sky with the sun on them, they are beautiful in a distant sort of way, but in my mind they will never have the awesome beauty of a man-of-war against a thunder sky or the ardent effort of a trawler against a heavy sea.
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Time was spent at RAF Medmenham watching experienced interpreters at work and visits made to RAF Benson to learn about air photography from the reconnaissance pilot’s viewpoint. Joan Bawden and Helga O’Brien had their first flight on their training course after a young Canadian pilot offered them a trip in a Blenheim bomber. Clambering up the footholds attached to the side of the aircraft, they squeezed into the little space available and were soon looking out on to an aerial view of Medmenham, enjoying the enormous noise of the engine and the wonderful sensation of speed.

Hazel Furney, Molly Upton and Sarah Churchill were invited for a flying trip in Tiger Moths by two pilot instructors at a nearby airfield:

Our heads were out in the open and the intercom was impossible to hear. At one point my pilot said something I couldn’t hear and, on the third attempt, I got the message that I was flying the aircraft, and we were losing height rapidly! After that incident, we caught the train to London and Sarah took us to see a show with Bebe Daniels and Ben Lyon, a well-known show business married couple who appeared in reviews. Afterwards we went to their dressing room and then on to Sarah’s flat.
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Having passed their final exams and been granted a commission, the new PIs received their first posting, either to RAF Medmenham or to a PRU base. Although they had worked hard and sometimes thought that they would get ‘thrown off the course’, the students must have found some time for socialising, as Shirley Eadon described:

One of the other WAAF officers on my course could swallow a pint of beer without stopping to draw breath. We used to take her around like a performing bear because, thanks to her, we all got free rounds of beer!
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All PIs at Medmenham held commissioned rank. Why was this considered necessary? A conference of senior PI officers held at the end of the war concluded:

If interpreters, if the actual men and women who hourly look at photographs, are too rigidly controlled and directed, either by their own organisation or by superior bodies, they will not be able to get out of interpretation all that it can give. The success of British interpretation is probably due first to the decision to use officers as interpreters and secondly to the give and take in the British character that permitted junior officers considerable freedom of initiative, and often responsibility, out of all proportion to their rank. For example, in the early days of the war, when a watch was being maintained on the German Fleet, the disposition of the entire British Fleet would wait upon the word of a single junior photographic interpreter.
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On the other hand, in the preface to her book
The Eye of Intelligence
, Ursula Powys-Lybbe refers to the tendency of ‘authorities’ to question a PI report when few would have the temerity to question the ‘intelligence snatched out of the air’ by the code and cipher school at Bletchley Park:

The basis for photographic intelligence, on the other hand, was the ordinary black and white photographic print familiar to the majority of people. It was therefore tempting for the recipients of Medmenham interpretation reports to borrow stereoscopic magnifiers and formulate their own opinions, sometimes overriding the findings of fully trained and experienced PI officers, particularly when the intelligence received was contrary to their expectations. In some cases our interpreters were ‘invited’ to rewrite their reports, an invitation which not unnaturally they refused.
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Most WAAFs who were to be commissioned attended the two-week course at the WAAF Officer Training Unit at Loughborough. Jeanne Adams:

We learned how and when to salute, to drill a squad, to be an orderly officer and to look after other ranks’ welfare. Last, but not least, to learn theoretically how to pass the port at mess dinners, which was a new experience for most of us. I was commissioned as Assistant Section Officer No 5086 and posted back to Medmenham.
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Jeanne found that there was another advantage to being an officer:

When I had my initial medical examination at the Air Ministry on joining up, I was handed a paste pot for a specimen by a dragon who said to me, ‘And don’t do it all over the floor’. At Loughborough we had a further medical and asked to provide another specimen. However on this occasion the orderly was far more courteous. I was handed a kidney dish covered with a cloth and the request, ‘Could you please provide a specimen, ma’am?’