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The Lockheed Electra 12A, registered G-AFTL, acquired by SIS (now MI6) for Sidney Cotton in 1939, and photographed outside the hanger of Airworks at Heston Aerodrome in west London.This is probably the most significant single aircraft in the history of aerial photographic intelligence, and remarkably still exists and still flies!



 For as long as there has been warfare, military commanders have relied on intelligence and reconnaissance to improve their odds in battle. Scouting was employed, if only from the nearest hilltop. When balloons capable of carrying a man were developed in the mid-nineteenth century, they were immediately employed for reconnaissance purposes, notably in the Franco-Prussian War of 1870. By using a camera, the observer could bring the evidence back down to the ground, but a balloon was not a particularly stable platform for the plate cameras of the day, a problem resolved by Count Ferdinand von Zeppelin with his rigid framed (dirigible) airship.  

The British military were slow to respond to both the balloon and the airship, its School of Ballooning not appearing until 1882, and experiments with dirigibles not until 1910. But the days of lighter than air craft as observation platforms were to be numbered when Wilbur and Orville Wright made their first powered flight in December 1903.  

Again the British military were slow to respond to the development of powered flight, and it was the public alarm at the development of German Zeppelins that forced the War Office to raise its game. The Royal Flying Corps was formed in April 1912, to develop aircraft, train pilots and to improve air photography. In August 1912, a young guardsman named Charles Victor Laws transferred from the Coldstream Guards to the RFC as an Air Mechanic/Photographer. 

Frederick Charles Victor Laws is now considered to be the founder and most prominent pioneer of British aerial reconnaissance. Already a keen amateur photographer, he started by taking pictures from Army airships of the 1st Airship Squadron, and discovered that vertical photos with 60% overlap could be used in a stereoscope to create 3D images, a significant advance.  

In 1914 Britain entered WWI aware that aerial reconnaissance would be of great tactical importance, but it had no optics, cameras, and few aircraft or pilots, and again was slow to respond. Eventually in 1915 Laws was placed in command of the new Royal Flying Corps School of Photography at Farnborough  where he created the first purpose designed cameras for aerial photography - the L (for Laws) and the L/B (for Laws/Brabazon). 

At the start of the war the early primitive aircraft were used for reconnaissance, initially with pilots only and soon with observers and cameras. At this stage there was little thought of the aircraft as an offensive weapon, but that changed almost immediately when British and French scouting planes were shot down from the ground or from the air. Air combat had begun. The pace of development on all sides was ferocious, and by 1918 scouts, fighters and bombers had become very sophisticated, as had the cameras and films used for air photography

At the end of the War – to end all wars – although the RFC had become the RAF, and now under the control of Hugh Trenchard it had to fight for its very survival. One of the first casualties of the cuts that followed was air photography, and the skills and technology ebbed away. Victor Laws, now RAF Squadron Leader, stayed on and managed to pursue the development of  the F8 and F24 air cameras, but disappointed at the continuing peacetime eclipse of his speciality, he resigned and left to work in the new world of commercial aerial survey. We will hear from him and his cameras again.


Although the military had now turned its back on aerial photography, the commercial world had not. In 1919 Aerofilms was established at Hendon Aerodrome by Francis Wills, Claude Graham-White and aviation pioneer Claude-Friese-Greene. Using a rented a De Havilland DH9 biplane, Aerofilms started in business filming flying sequences for the new movie industry, but by its second year had tapped into a new and lucrative vanity market providing aerial photographs of country houses, palaces, municipal buildings and factories. 

Whilst Aerofilms was finding its feet, one of the many pilots that had been trained during the war and who were finding civilian life tame, was a straight-talking Australian named Sydney Cotton. Son of a wealthy Queensland cattle rancher, Cotton joined the Royal Naval Air Service in 1915 and showed considerable aptitude as a pilot and engineer. His single-minded approach to problem solving soon brought him into conflict with his superiors, and he resigned his commission before being discharged, and returned to Australia, but not before he had invented what was to become the ubiquitous “Sidcot” flying suit, which kept pilots warm until the 1950’s. The “Red” Baron von Richthofen was shot down wearing one of Cotton’s flying suits!  

Sydney Cotton returned to Britain, having fallen out with his father over the family business, and now in need of an income of his own, answered an advert placed in the “Aeroplane” magazine in 1920:    “Pilot Wanted – plenty of risk, good pay”,  and soon found himself seal-spotting in Newfoundland. The seal-spotting was not a huge success, but the establishment of an aerial survey and mail flying was; Cotton needed more investment and returned to the UK and raised funding through a wealthy young flyer, Alan Butler, who had inherited the family coal briquette business on the death of his father. Butler promptly sold the business and made himself a very wealthy young man. Butler and his money joined Cotton in Newfoundland for the prospect of some challenging flying, rather than any interest in the business venture. Neither Cotton nor Butler had experience in aerial photography, and Cotton engaged the services of another WW1 pilot, Major Harold “Lemnos” Hemming, whom he had met during the war, and had been involved in a similar spotting venture in 1919 in Bermuda, though also without much success.  

Cotton persevered with his seal-spotting and timber interests, but Butler and Hemming returned to England, and established the Aircraft Operating Company in 1923 at Bush House, in London, to exploit the possibilities of aerial photography for survey and mapping. In the end Cotton abandoned his Canadian interests, to pursue a number of money-making schemes, but we will hear from him again. 

On his return to the Britain, Butler ordered a private aircraft, to his own specification for the new sport of air-racing, (a pursuit he shared with Cotton and Hemming) from the new De Havilland company, and impressed by its potential, agreed to make a substantial investment and as a result he was promptly appointed its chairman - a role he held until his retirement in 1970!  

The Aircraft Operating Company, with Butler as chairman and Hemming as Managing Director, was thriving, and in 1925 took over Aerofilms, and expanded its operations at Hendon, surveying for the Ordnance Survey and in British Overseas colonies in the Middle East, Africa, Asia and Brazil. In 1933 the Aircraft Operating Company and Aerofilms were incorporated into a new company, H Hemming and Partners, and now based at Aerofilms’  headquarters on Beresford Avenue, Wembley, at which time the shipping and aviation entrepreneur, Sir Percy Hunting took a stake in the business. The new company undertook a major contract to survey Western Australia, and appointed none other than Squadron Leader Victor Laws as Expedition Leader, using two rented DH 84 Dragon aircraft. 

By 1938 Hemming and Partners was now in a position to purchase a new and very expensive Swiss-made Wild A5 Autograph photogrammetric plotting machine that could, in effect, turn aerial photographs into maps. It was also a very effective tool in photographic interpretation, and was destined to have a major impact on events in the very near future. Its purchase can only be described as inspired. 

But as far as the armed services were concerned, air photography remained a backwater. The newly formed RAF had maintained the responsibility for aerial reconnaissance for the three services, with photo interpretation being undertaken by the Army at Farnborough, but funding for the new service was severely reduced during the 1920’s. The Royal Naval Air Service, created during WW1 was incorporated into the RAF, and as a result the Navy had no ability to undertake reconnaissance of its own, relying on the RAF to take pictures, and the Army to interpret them!   With British foreign policy towards Germany during the 1930’s being one of appeasement, aerial surveys of its growing mobilisation were not undertaken. During this period, for what little photography was done, the RAF used the aged, slow but manoeuvrable Westland Lysander, and the recently introduced twin-engined Bristol Blenheim, capable of 250mph. With the F8 and F24 cameras, 8 inch lenses and the aero films then available, air photographs were taken at a maximum ceiling of 12,000 feet to produce an image scale of 1:10,000. Quite acceptable parameters in peacetime, but any aircraft in war-time flying low and slow would be vulnerable to being shot down, by fighters or anti-aircraft fire, a lesson that had already been learnt, and now forgotten, in WW1.   


But despite official British foreign policy, British Intelligence were concerned about potential aggression from Germany and Italy, and created the Air Section of the SIS (now MI6) to acquire information on military build-up in potentially hostile countries. They recruited another former WW1 pilot, Frederick Winterbotham to run the new section in1930.  

Winterbotham  had enlisted for service at the start of WW1, transferred to  the Royal Flying Corps and became a fighter pilot, and was shot down and captured in 1917 and spent the rest of the war in a German POW camp, where, to pass the time, he learned German. After the war he pursued farming opportunities in Australia and South Africa, but returned to Britain in 1929, before re-joining the RAF and MI6. With his cover as an RAF officer with Nazi sympathies he was able to ingratiate himself with the new Nazi regime, and set up a network of agents. 

In 1938 at the time of what is now called the “Munich Crisis” - when war with Germany seemed a real possibility, Winterbotham was charged with gaining photographic intelligence of military build-up in the axis nations, as the possibility of using agents on the ground became increasingly difficult. He discussed the problem with his opposite number in French Intelligence, Colonel George Ronin of the Deuxieme Bureau, which had already made attempts to survey the Rhineland and the Siegfried Line, but with little success, and they agreed to collaborate. Despite Neville Chamberlain’s “peace in our time” speech to Parliament in September 1938, Winterbotham came under increasing pressure, in particular from Winston Churchill and his “Chartwell Group”, to provide immediate aerial intelligence of Germany’s military build-up.     

Winterbotham and Cronin had had dealings with an American arms dealer, A J Miranda, of the American Armament Corporation, who was under investigation by a US Senate Committee on suspicion of breaching US arms embargos, and therefore seemed like the ideal candidate to locate an aerial survey contractor who would not ask too many questions. Miranda put them in touch with a former naval pilot and entrepreneur with whom he had traded aircraft in the past and who had recent survey experience and with a convincing cover story.  

This man was an Australian who had already fallen out with the Royal Naval Air Service in 1917, who had considered him “not suitable for military service”, and was, of course Sydney Cotton, who we left in Canada in 1923, since when he had been involved in  a series of mainly aviation-based adventures, making fortunes and losing fortunes, but in particular had spent several years attempting to develop Dufay Color Film , which had involved him flying his own aircraft through Europe to sell the process, and in particular into Germany. But by 1938 he had fallen out with his associates and he was running out of money.   

The plan hatched by Ronin and Winterbotham required not only a businessman with a suitable cover story but also an aircraft that would not cause suspicion. Cotton, his film business and Twin Beech aeroplane, based at Heston Aerodrome in London, seemed ideal, and he was approached through Miranda’s agent in Paris, Paul Koster, who arranged for him to meet Winterbotham in London. Winterbotham explained that Cotton would be well paid for his cover and aircraft, and that he could continue to make flights into Europe, but actual reconnaissance flights would be carried out by a French crew. Cotton, on the basis of French incompetence in flying and photography soon convinced Winterbotham that he should do all the flying himself, and that his Beechcraft should be replaced by the latest American Lockheed Electra twin-engined junior airliner, which his friend Miranda was happy to supply……. 

Cotton, and a Canadian pilot, Bob Niven, recruited by Winterbotham were able to make a number of “business trips” into Germany, with the Lockheed crudely modified to take a vast and ancient French camera, without much success, and at great risk if the camera were to be found by the German authorities. Cotton abandoned the French camera and was able successfully to photograph many strategic targets using no more than hand-held Leica cameras. The image quality was good but too small a scale for detailed assessment. However the relationship with the French Secret Service soon became unworkable, and Winterbotham agreed with Cotton’s proposal to abandon the French to their own devices and acquire another Lockheed and work independently. 

To avoid suspicion the order for this second aircraft, again supplied by Miranda, was placed by the To newly formed British Airways, and a hangar was rented at Heston Aerodrome where Cotton already kept his own aircraft. The Lockheed Electra 12A, registered G-AFTL was delivered in May 1939, by which time the Germans had invaded Czechoslovakia, and war was now almost inevitable. The aircraft was modified by Airwork Ltd at Heston to accept additional fuel tanks and provision for hidden RAF F24 cameras in the wings and fuselage, and re-painted in the duck-egg blue “camouflage” colour that Cotton had registered as “Camotint”. Cotton had copied the colour from an aircraft that he sold to Maharajah of Jodhpur, and had been impressed by how soon it was lost in the sky. 

Winterbotham had decided that the first task for what was to become known as the “Secret Flight” was an extensive survey of the Mediterranean and the Middle East, with Cotton’s cover now as a movie mogul scouting locations, or an Imperial Airways executive testing new routes, as appropriate.

This expedition in June 1939 proved very successful, in terms of the quality of the photographs and evidence of military build–up. Cotton and Niven were joined in Malta by another RAF pilot, Maurice “Shorty” Longbottom. Whilst the three men were together they came up with a set of proposals for the future of aerial photographic reconnaissance, that seem obvious now, but which were radical at the time, and definitely “not invented here” as far as the RAF were concerned.  

After the success of the “test-run” to the Middle East, Cotton and Winterbotham agreed to test Cotton’s cover to the limit, on the basis of tying up a deal on the Dufay Color Film process in Germany. On the 26th July 1939 Cotton and Niven flew from Heston to Berlin without the bulky F24 cameras, but with two Leica Reporter 250 motor-drive cameras hidden in the wings. They were met at Templehof Airport by Nazi soldiers, but their obvious concerns were allayed when it turned out to an honour guard for their distinguished guests! Despite the Lockheed being guarded overnight by the Gestapo, nothing untoward was found, and they returned to Heston the following day.  

Over the next few months, Cotton and Niven were able to make many more flights into Germany, with great success. The cover story and the luxurious and ultra-modern Lockheed were so convincing that Cotton was asked to demonstrate it to a number of senior officials, which he was pleased to do. Their presence enabled him to secretly photograph sensitive locations, using camera controls hidden under his seat! There must have been real concerns in MI6, however, that Cotton’s luck would run out – he was after all a civilian, and the consequences of detection would be very unpleasant indeed, but one morel flight was made on the 22nd August 1939. Their luck very nearly did run out; whilst in Berlin the Russo-German Non-Aggression pact was signed – on the 24th August - and with all civilian air traffic now grounded they saw little prospect of an early return to Britain. But at the last minute the Lockheed was given permission, probably by Goering himself, to take off, but with very specific routeing back to Britain, with threats of being shot down should they deviate.      

As they crossed the Dutch border at Groenigen, they caught sight of the German fleet 50 miles away at Wilhemshaven. They could not resist the temptation to take what turned out to be very good pictures of the German fleet in readiness, despite the risks of being attacked by the Luftwaffe.  

Cotton’s Lockheed was the last civilian aircraft out of Berlin! The Admiralty and the Air Ministry were impressed with the pictures – taken with hand-held Leicas -  and asked Winterbotham to arrange photography of German shipping in Heligoland, which was done on 27th August, this time with the F24 cameras re-installed, with the cover story, if required, of a meeting in Copenhagen on Dufay business. Again Cotton and Niven returned with good images and Naval Intelligence requested that the “Special Flight” return to Wilhemshaven, a flight which was completed on the 1st September, by Niven, flying alone in Cotton’s Beechcraft. These pictures established that the German fleet sighted by Cotton earlier had not yet moved - although subsequently it became apparent the Graf Spee had left in the last days of August.   


Germany invaded Poland on the 1st September, and war was declared on Sunday 3rd September. Winston Churchill was immediately appointed First Lord of the Admiralty, prompting a signal to be sent to the Navy “Winston’s back!”   The RAF had been standing-by with a reconnaissance Blenheim, which took off for Wilhemshaven within an hour of the declaration, to provide the intelligence required to make a pre-emptive attack on the German fleet before it was able to leave for the Atlantic. The Blenheim’s cameras and radio froze, and the subsequent “blind” attack was not a success. Churchill was not impressed. 

With Britain now at war, Cotton might have expected that his brief photographic spying career might have come to an end…….. 

During “Special Flight’s” Middle East trip in June, Cotton, Niven and Maurice “Shorty” Longbottom’s discussions about  the future of successful aerial reconnaissance were written up into what became known as the “Longbottom Memorandum”, and as the only serving officer, Longbottom submitted it to the  Air Ministry entitled “Photographic Reconnaissance of Enemy Territory during War”   Despite the lessons of the First World War, the conventional wisdom at the Air Ministry and the RAF was that to achieve photographs of a size and resolution to be of any value for intelligence purposes, the aircraft would of necessity be required to fly low and slow. Detection would be inevitable, and the resulting heavy losses would be minimised by using well-armed bombers, and although the Blenheim bomber had been introduced as recently as 1937, it was still very slow at 250mph. On that basis, no attempts had been made to improve the capabilities of the cameras or aero films. But although the British government’s position remained one of appeasement, pressure from Churchill, in particular, had resulted in the commissioning of new fighter aircraft for the RAF in 1935. The Hawker Hurricane first flew in 1935, and the Supermarine Spitfire made its first flight on 5th March 1936. Both were powered by the Rolls-Royce Merlin engine, whose technology had been developed for the Schneider Cup air races. The combination of the Spitfire airframe and the power of the Merlin engine provided a step change in fighter performance, and significantly a much higher service ceiling…….. 

Longbottom proposed that aerial photographic reconnaissance would be more effectively achieved by avoiding enemy aircraft and anti-aircraft defences altogether, and the best way to do that was to fly high and fast. He suggested that a suitably camouflaged modern single seater fighter – a Spitfire, for example – stripped of its armament and radio could rely on speed and altitude to avoid enemy fighters. The RAF put Longbottom’s report was placed on file….. 

Within two weeks of the outbreak of war, Cotton got a phone call from his Secret Service boss, Winterbotham; The Air Ministry wanted to see them both as a matter of urgency. The RAF was under relentless pressure from Churchill for results – its early attempts at aerial reconnaissance for the Navy having resulted in fogged film and frozen cameras and unacceptable aircraft losses. What special equipment, they asked Cotton, was he using to obtain such good results? Cotton explained that he was using standard RAF F24 cameras, as supplied by them, and by ducting warm air from the Lockheed’s heated cabin they had been able to keep the lenses fog free.   Cotton’s suggestion that the RAF’s failure was as a result of policy and neglect in the years running up to the war, was met with disdain. Cotton was making no friends in the Air Council. Even at this stage he was considered  divisive and troublesome, but he and Niven were producing results, and without loss.

Cotton was taken to Air Vice marshal Sir Cyril Newall, Chief of the Air Staff. Newall asked Cotton to take over the RAF Photographic section. Cotton declined but offered to set up a special unit to develop high altitude, high speed photographic reconnaissance, provided that he had carte blanche to choose equipment, men and aircraft, using the principles of the Longbottom Memorandum, and based at the civilian Heston Aerodrome – in the interests of secrecy

Churchill’s demands for aerial photography were such that Newall had little alternative but to accept Cotton’s proposition. On 22nd September responsibility for the “Special Flight” moved from MI6 to RAF Fighter Command and Cotton was commissioned with immediate effect into the RAF as a Squadron Leader, with the acting rank of Wing Commander. He immediately recruited Bob Niven and Maurice  Longbottom, and a team of photographic technicians from the Royal Aircraft Establishment at Farnborough, and the secret unit started business at Heston Aerodrome, in the hangar of Airwork Ltd, the flying club and part of the Airport Hotel. Film processing would be undertaken by the RAE at Farnborough initially, although suitable equipment would arrive in due course.

At this stage Cotton’s secret unit, now designated the “Heston Flight”, had “his” (or more accurately MI6’s) Lockheed Electra, his own Twin Beech, plus a single-engined Beech Staggerwing, also owned by Cotton. His initial request for two Spitfires was met (not surprisingly in September 1939) with derision. He was offered two Blenheims, and told to get on with it. By using the process that became known as “Cottonising” – careful attention to drag, removal of gaps and projections, low friction paint, etc – the Heston team were able to increase its speed by 25mph. But he needed 400 mph, and that was clearly beyond the Blenheim. But the effectiveness of “Cottonising” had reached Air Chief Marshal Sir Hugh Dowding, Commander in Chief, Fighter Command, who was trying to turn the Blenheim into a long-range fighter. Dowding was sufficiently impressed to ask Cotton how he could help the Heston Flight, and in response to his almost light-hearted request for two Spitfires, Dowding, according to Cotton’s  account, replied after a lengthy pause – “When do you want them?” 

Two Spitfires arrived at Heston the following day, but  Dowding’s enthusiasm for Cotton’s ideas was not shared by the Air Ministry - and both Dowding and Cotton’s careers would suffer as a result. The Heston team set about” Cottonising” the Spitfires and with the removal of the armament, radio and armour plating increased the speed from 360 to 396 mph. An additional fuel tank under the pilot’s seat increased the range to 1250 miles, plus the F24 camera installation completed by Harry Stringer at Farnborough. They were painted in the “Camotint” colour that was registered by Cotton, and would eventually be described as ”PRU Blue”.  By the end of October 1939, Cotton had two Spitfires capable of cruising at 400 mph at 30,000 feet with a range of 1250 miles, fitted with the best (at the time) cameras that were available.  

The technicians at the RAE initially were not prepared to fit the additional fuel tanks and 64lbs of camera installation on the basis that the aircraft would be outside its design weight and balance – until Cotton pointed out that all Spitfires that were using the newer 3 blade steel propeller had 32 lbs of ballast in the tail, the removal of which restored the centre of gravity!  

The Heston Flight was cryptically re-designated No 2 Camouflage Unit by Fighter Command and flew its first photographic sortie on 18th November 1939, when Shorty Longbottom took off from Seclin near Lille, to photograph sites in neutral Belgium. The event was described later by Constance Babington-Smith as “an historic occasion, for the first time successful exposures had been made at high altitude under war conditions by cameras mounted in a Spitfire”  Longbottom’s pictures had, in fact been taken at 33,000 feet. 

Impressive as Cotton’s unit’s pictures were, the scale was limited by the 8 inch focal length lens which was then the longest lens for the F24 camera, and by its 5 x 5 inch film format. The Air Ministry considered this scale, at about 1/70,000 of little use for detailed interpretation, but still better than the RAF had hitherto produced. Aware of the potential of his associate Harold Hemmings’ Aircraft Operating Company, Cotton proposed that to the Ministry they be used to improve image resolution. Hemming had, in fact, already offered the services of his company to the Air Ministry as early as 1938, and again in 1939, but had been turned down because the Ministry chiefs were unable to shake themselves out of the “this is how we do aerial reconnaissance” attitude.

The Ministry turned down Cotton’s request, and in what was becoming his usual style, he ignored his superiors and engaged the Aircraft Operating Company on a private basis. Using the Wild Autograph machine, Hemmings’ operators were able to “boost” the images up to ten fold, and soon the output from Cotton’s satellite unit now based in France (now called the “Special Survey Flight”, and later 212 Squadron – the Heston operations were now called the Photographic Development Unit, or PDU) and flying deep into Belgium and Germany, could be returned to Wembley for interpretation.  

Cotton made repeated requests to expand the Photographic Development Unit with more Spitfires and  formally  acquire  the Aircraft Operating Company and its team of interpreters, but made little apparent progress. (At the outbreak of war the RAF had just seven photographic interpreters based at Bomber Command. A training centre was set up initially at the Air Ministry in London, but moved to Hibbert Road School in Wealdstone, near Harrow).   

In early January 1940, a conference was convened by the Air Council to review the current state of photographic reconnaissance; although the Air Ministry were loath to admit it, Cotton’s “experimental” unit was providing real results with no losses (during this “phoney war” period, seven squadrons of RAF Bristol Blenheims had flown 89 sorties over enemy territory, only half of which had produced any pictures, at the cost of sixteen aircraft and crews. Cotton, Niven and Longbottom had returned from all of their sorties, without loss. The effectiveness of what was being described by the RAF’s senior officers as “Cotton’s Flying Circus” could not be denied, but  little progress was made and the Air Ministry continued to dither, but were shortly to be overtaken by events, or rather by Winston Churchill…. 

Although the Admiralty had recovered control of the Fleet Air Arm in 1937, it was still dependent on the RAF for photo reconnaissance. Naval Intelligence were well aware of Cotton’s successes (and in fact had already used his services through Ian Fleming, who had been seconded to Naval Intelligence), and having had the RAF fail to provide photographs to establish whether Tirpitz had left Wilhemshaven, commissioned “Cotton’s Flying Circus” to do the job.” Shorty” Longbottom flew the mission to identify Tirpitz, flying at 35,000 feet. Returning to Heston, Cotton took the film to Wembley for processing and interpretation, using the Wild machine. The image that was produced to an effective scale of 1/10,000 showed Tirpitz still in dry dock. The impact of this mission on Winston Churchill was immediate. If the Air Ministry and the RAF would not support the PDU and Hemming’s AOC in Wembley, then the Admiralty would.  

The effect was immediate; Cotton got the Spitfires that he had requested; the Aircraft Operating Company (AOC) was acquired by the RAF, which took over the training of interpreters in Wembley, (under the control of newly commissioned  Wing Commander Hemming) now known as the Photographic Development Interpretation Unit. The RAF interpretation and training unit at Hibbert Road was absorbed immediately into the Aircraft Operating Company in Wembley, and were joined by a former AOC interpreter, Douglas Kendall, who had worked with Cotton in France. He would go on to head up photographic interpretation, firstly at Wembley, and then at Medmenham. 

By  the beginning of April 1940, new long range purpose-built Spitfires were delivered to Sidney Cotton’s “airforce” at Heston, now with wing mounted fuel tanks and F24 cameras with 8 inch focal length cameras. The PDU was growing very fast, from 8 officers to 21, and from 19 to 171 other ranks between September 1939 and February 1940, and in an attempt to impose some control the Air Ministry appointed Squadron Leader Geoffrey Tuttle to be Cotton’s administrative assistant at Heston. Cotton welcomed Tuttle’s arrival, even though he had been tasked by Fighter Command “to impose military discipline on “Cotton’s Crooks”.”  

The Aircraft Operating Company in Wembley was now part of the RAF, into which its staff  were recruited, and was now referred to as PADUOC House (an acronym based on PDU and AOC) By June 1940 the staff at PADUOC House had reached 122, involved in all aspects of film processing Interpretation and training. But, like Cotton’s PDU it had a former civilian at its head, and this did not fit well with the RAF.  

Following the Air Ministry conference in January 1940, Victor Laws (now Wing Commander) was appointed Deputy Director of Intelligence at the Air Ministry with responsibility for photography to address the technical issues of the rapidly changing requirements for aerial reconnaissance that were being imposed by the reluctant acceptance of the Longbottom Memorandum and the success of Cotton’s Flying Circus, and this led to establishment by Sir Henry Tizard of the Air Photography Research Committee, and included technical experts from Eastman Kodak and Ilford Ltd, to improve the quality of film stock, simplify and speed up processing, improve the optical systems, cameras and installations, and establish a means of determining correct exposure under day and night conditions, at high altitude and high speeds.    

In layman’s terms the Air Photography Research Committee’s objective was find the technology to be able  to “identify a man on a bike from 35,000 feet at 400 mph”. The Committee’s secretary was Kodak’s Dr Douglas Spencer, and its senior member Roy Davies, Head of the Kodak Research Laboratory, who commissioned the work by Edward Selwyn and John Tearle, subsequently published as “The Performance of Aircraft Lenses”, that formed the basis of the ultra-long focal length F52 camera, built by Kodak, that by 1941 was installed in the PRU Spitfires and Mosquitos, that amongst many other things found Germany’s revenge weapons V1 and V2.     Although Cotton’s PDU was now part of the RAF, it still retained its link with MI6. Between the evacuation at Dunkirk and the fall of Paris in June of 1940, Winterbotham used Cotton and the Lockheed Electra for a number of clandestine operations to evacuate important members of the intelligence community. Cotton had always had a free rein from Winterbotham, and used the opportunity to recover other assets of a more private and commercial nature, or at least that was the accusation that was thrown at him, and it was to be his undoing……  

As Cotton and his team hastily wound up their operations in France, with the fall of Paris, he returned to Heston on 17th June to be told by letter that on the basis that his unit was no longer experimental it would be absorbed fully into the RAF with the new title of the Photographic Reconnaissance Unit, and under the command of Wing Commander Geoffrey Tuttle. The RAF had got its way. 


Sydney Cotton, Shorty Longbottom and Bob Niven had changed transformed aerial reconnaissance in nine months. The impact of the PRU was to be as profound as the intelligence gathering at Bletchley Park, yet Cotton was sacked in a quite outrageous manner. Cotton was a buccaneer, an adventurer and an entrepreneur. His interest in aerial reconnaissance was to make his ideas happen, not to make a career in the RAF. It is unlikely that anyone else could have achieved the same results, but he had out-shined and upset too many of the RAF and Air Ministry’s top-brass and he had to go.

Professor R V Jones, head of British Scientific Intelligence from 1939 -1945, said of Cotton, in his book, “Most Secret War”:   “Cotton, who had a genius for getting things done – and frequently doing the himself – had seen where the effort needed to be made; fast high flying aircraft of long range, with good cameras and outstanding pilots, and with specialist interpreters for examining the photographs. Before long his irregular methods were too much for the RAF, and he was “organised out” of his leadership of photographic reconnaissance. He had a raw deal, for his contribution was great: and I for one am glad to have known him”  

Although the Air Ministry had promised to find other avenues for Cotton’s outstanding skills, it never happened, and he sat out  the rest of the war. In1946 he returned to his buccaneering exploits with sometimes hair-raising results, see-sawing between financial disaster and great wealth. He died in 1969 in distinctly straightened circumstances. He was rather churlishly awarded an OBE in 1941. Perhaps because of his colourful lifestyle and his life-long run in with authority, he has never received the recognition that is due to him, either in Britain or his native Australia. 

From mid-1940, the Photographic Reconnaissance Unit at Heston was expanded by the very capable Wing Commander Tuttle, with an ever increasing inventory of aircraft, pilots and technicians. Pilots were selected on their ability to navigate for hours without visual references and by compass and map alone. They flew without radio or armament. Their sole purpose was to return with pictures after many hours in the air and in freezing conditions. All had combat experience, and in general were volunteers for a very solitary existence. 

By the autumn of 1940, Heston and Wembley were becoming dangerous places to be; both had been bombed, and most of the vital staff at PADUOC House lived locally. Tuttle’s Photographic Reconnaissance Unit was relocated to RAF Benson in Oxfordshire and became No 1 Photographic Reconnaissance Unit, or 1 PRU. The Spitfires were joined by Blenheims, Lockheed Hudsons and critically by De Havilland Mosquitos in 1942. PRU operations rapidly expanded to every theatre of war, but retained the basic principles of speed and height to avoid detection.    

At PADUOC  in Wembley, Hemming had been given the task of re-locating his growing empire to a safe and secure location outside of London. By chance he stumbled on Danesfield House at Medmenham in Buckinghamshire, which was requisitioned and the RAF Photographic Interpretation Unit moved in during April 1941, and was re-named the Central Interpretation Unit (CIU). Once this had been achieved the RAF took the opportunity to ditch Hemming in the same insensitive way that Cotton had been removed. The same fate did not, however, befall Douglas Kendall, who had worked with Hemming for many years – he was just too good and remained Head of interpretation until the end of the war. It is quite remarkable that just one person in the CIU was “Ultra cleared”, that is, was privy to the intelligence that was being generated by Enigma intercepts, and that person was Harold Hemming’s early recruit and who worked for Sidney Cotton in France in 1940, Douglas Kendall.  


By 1945 CIU at Medmenham handled 25,000 and 60,000 prints per day, by which time it had become the Allied Central Interpretation Unit with 1,700 personnel on its strength. By the end of the war it handled all Allied photographic intelligence and formed the template for United States aerial reconnaissance interpretation.  The principles of aerial reconnaissance photography set down in the Longbottom Memorandum have continued until the present day, although the photography is undertaken by satellites as well as the stealth aircraft that are the descendants of Sydney Cotton’s two Spitfires that first took pictures in 1939.  

The F52 camera developed by Kodak and the Royal Aircraft Establishment stayed in service through the Cold War.  I PRU continued to fly the blue Spitfires out of RAF Benson until April 1954, when they were withdrawn from service, but not before they had been spotted by a schoolboy in Harrow Weald.............     

A considerable debt is owed to Cotton, Longbottom, Winterbotham, Laws, Hemming, Kendall, and a great many brave pilots.   

And now I know how Kodak’s (Selwyn, John Tearle and others) research work turned a possibility into reality, what the Blue Spitfire was doing, and what was achieved in Medmenham!  


Eyes of the RAF, Roy Conyers Nesbit
Aviator Extraordinary, The Sydney Cotton Story, Ralph Barker
Operation Crossbow, Allan Williams
Spies in the Sky: the secret battle for aerial intelligence in WWII, Taylor Downing
Images of Conflict: Military Aerial Photography and Archaeology
Legends and Heroes; Behind the Lens, Dave Humphrey
The Ultra Secret, Fred Winterbotham
Most Secret War, R V Jones
Air Photography in War, Flight, August 1942, F C V Laws
F C V Laws; Wikipedia
F24 Camera: Wikipedia
Air Cameras: www,airrrecce.co.uk
RAF Reconnaissance Aircraft, Part 1, Part 2 www,airrecce.co.uk
RAF Medmenham: Wikipedia
No 1 PRU: Wikipedia
Aircraft Operating Company:Wikipedia
Aerofilms: Britain from above
British Airways Ltd (1935-39)
F W Winterbotham: Wikipedia
BBC: WW2 People’s War My 9 months with Sydney Cotton’s Private Air Force
Mrs M J Cotton: Speedqueens
Sydney Cotton: The last plane out of Berlin: Jeffrey Watson
Above All Unseen: Royal Air Forces’s Photographic Reconnaissance Operations 1939-45: Edward Leaf
Spitfire’s Forgotten Designer: The career of Supermarine’s Joe Smith Spitfire: Tony Holmes
The Influence of the Dimensional Properties of Photographic Objectives on their Photographic Resolving Power: Ph.D. Thesis, J. L.Tearle, University of London, January 1944
The Performance of Aircraft Camera Lenses: E.W.H. Selwyn and J. L. Tearle, proceedings of the Physical Society, March 1946
Definition in Air Photographs: J.L.Tearle: Institut d’Optique, Paris, 1946
Photographic Aspects of Air Survey: G.C. Brock, Royal Aircraft Establishment, The Photographic Journal, December 1952.

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