27 December 2023 to 25 February 2024

IWM Duxford


Spotlight exhibition with general admission

Free entry for IWM members
Aircraft contained in the Spies In The Skies spotlight exhibition

Spies in the Skies: Second World War Aerial Reconnaissance shines a spotlight on the squadrons tasked with flying behind enemy lines to gather intelligence from the air. 

The Photographic Reconnaissance Unit (PRU) would operate far behind enemy lines in specialised aircraft. They would often fly unarmed, with their weapons swapped for high-performance cameras.

This winter, discover the incredible stories of the crew and aircraft who gathered crucial information from the war-torn skies of Europe.  Learn the history of RAF aerial reconnaissance and get up close to the PRU's aircraft, gathered together under one roof.

Behind enemy lines

Replica of a pink PRU unit Spitfire

80% of intelligence gathered in the Second World War came through photographic reconnaissance. The PRU's work was invaluable to Allied war efforts but came at a great cost, with the unit suffering one of the highest loss ratios of the war.

From the location of the German battleship Tirpitz to the existence of the newly developed V-1 Flying Bomb, the information gathered by the PRU was instrumental in the Allied victory.

Sidney Cotton's Lockheed Electra

The story of Sidney Cotton, his Lockheed 12A Electra Junior and the birth of the RAF's Photographic Reconnaissance Unit.

Looks can be deceiving and it may not be apparent on first inspection of this civilian aircraft, in its civilian livery and non-military markings, that this was one of Britain's first spy planes. This is the Lockheed Electra 12. The Lockheed Electra was a perfect camera platform. It could be fitted with cameras in the cabin and in the leading edge of the wing and it meant that with its inconspicuous livery, in the years before the Second World War, this aircraft would have gone relatively unnoticed in the skies of Europe. Reconnaissance was incredibly important in times of warfare, and in the 1930s, as Germany became more closed off to the rest of the world, reconnaissance from a ground perspective became virtually impossible.

Photo reconnaissance is often a form of intelligence that is overlooked or not really understood. It's not just the taking of the images but it's the interpretation of what has been taken that is so crucial. It's actually said that around about 80% of all Britain's wartime intelligence actually was taken from photo reconnaissance and that began with the Electra 12. Just a few days before Germany's invasion of Poland, this aircraft was in Berlin. When it departed Berlin it was the last British civilian aircraft to depart before the outbreak of the war.

The Lockheed 12 was the follow on to the very successful Lockheed 10, 10 seater, that is always going to be heavily linked to the story of Amelia Earhart and her co-pilot Fred Noonan. Flying a Lockheed Electra 10, Amelia Earhart and her co-pilot were attempting to circumnavigate the globe, when on what was virtually their last leg on the 2nd of July 1937, communication was lost and the mystery of what happened to them that day has not been solved. Despite this high-profile loss, between 1936 and in 1941 around 130 Electra 12s were produced. Both the Lockheed Electra 10 and the Lockheed 12 remain popular aircraft in civilian hands.

Reconnaissance in time of war has always been hugely important from the earliest introduction of flying machines, be they balloons or heavier than air aircraft, this type of reconnaissance could then be carried out over the horizon. From the start of the First World War, aircraft began to be equipped with cameras, initially handheld and eventually actually attached to the aircraft. This allowed mapping of the trench networks and again a better use of that type of intelligence.

By the mid-30s most aerial reconnaissance in the RAF was done by just a handful of people. Despite the RAF having designated aircraft capable of taking aerial photographs, in the years before the Second World War, as tensions with Germany grew, flying a military aircraft over their airspace was just not possible, hence why a civilian aircraft would fill that need. The Lockheed 12 was equipped with six luxurious and comfortable seats and a lavatory in the rear of the aircraft. Capitalizing on the innovations at the time, the aircraft was also quite fast and it had a reasonable range as well, for flying corporate passengers across the US.

There are many myths and legends that have built up around this aircraft, but a name that will always be associated with this particular Lockheed 12 is Sidney Cotton. After the start of the First World War, Sidney Cotton, an Australian businessman, would enlist in the British forces joining the Royal Naval Air Service as a pilot. As a result of his experiences flying during the First World War, he came to realize that the pilot's equipment of the day was not adequate. This experience led him to design the first bespoke one-piece flying suit. The Sidcot Suit would become very popular with pilots, but it has led on to advances in flight suit technology that we see modern-day fighter pilots wearing today.

After the end of the First World War, Sidney Cotton would remain involved in aviation getting involved in photo mapping, where his first involvement with cameras on airplanes began. Sidney Cotton would become involved with Dufaycolor - an early colour film processing technique. Having obtained the rights to sell Dufaycolor outside of France, he was regularly flying business trips into Europe and it's around this time that he is approached by MI6 and asked to actually start undertaking these flights. His initial flights with the French were not overly successful. The aircraft themselves were loathed to fly beyond the frontier and the camera equipment and the camera operator often didn't take photographs of the key military installations. This led Sidney Cotton to essentially state that for this job to be done properly he needed his own aircraft and his own crew. This would be provided, through elicit means, by MI6, leading to the purchase of this aircraft.

When he was given his aircraft - Golf, Alpha, Foxtrot, Tango, Lemma, he made a number of modifications to it. One was to have a panel removed from the cabin door so photographs could be taken whilst in flight. Two panels were also created underneath the aircraft for downward looking F24 cameras and there was provision also for two Leica cameras fitted within the leading edge inboard of the engines. So we've come over to the stores here at Duxford, to take a look at an item in the museum collection. In this case, an Air Ministry aerial camera.

I think it was an F24 automatic camera, vertical camera and it was to... as I was a photographic reconnaissance operator, later pilot, later it would have given a very small scale picture, but enough for what our boys wanted it for. This type of camera would have been fitted in the underneath of the Lockheed Electra facing down. When fitted on aircraft they would have been been set so that they overlapped. That would mean that two images taken next to each other could be looked at together through a stereoscopic viewer and the stereoscopic viewer would allow interpretation of the image by looking at things like heights, shadows, by almost giving a 3D effect through that viewer. The RAF at this time were struggling keeping their cameras working when flying at altitude or in cold temperatures and he came up with an innovation whereby hot air ducted from the engines was blown over the cameras to remove condensation and to remove the risk of freezing up.

The size of the Electra 12's cabin also allowed for the provision of additional fuel tanks and rumours say that he possibly fitted as many as two extra tanks behind the pilot and co-pilot and there's certainly evidence that one of those was fitted to increase the range and therefore the endurance of the photographic sorties. Despite being in the employer of MI6, he was able to fly his civilian registered Electra 12 with relative immunity over the skies of Europe.

When flying over Germany, his flight plans were dictated by the German government, but he often managed to negotiate and arrange for his flights to go off track to areas that he wanted to photograph. On a number of occasions he flew high ranking German dignitaries and members of the military forces on board the aircraft and there are rumours that whilst they were on board, he also was able to take photographs of the installations they were flying over. Using his cover promoting his film business, he was often able to fly his airplane to locations that would be out of the reach of many other individuals and organizations.

The RAF's two main reconnaissance aircraft at the time would have been the Westland Lysander and the Bristol Blenheim. The Lysander was a very stable but slow aircraft. The Bristol Blenheim, on the other hand, while a little bit quicker, was required to fly relatively low to undertake its aerial reconnaissance missions and this was something Sidney Cotton wanted to move away from. Through experimentation with different types of cameras, different types of lenses, he was able to maintain blowing air over the cameras themselves to stop them from condensing at the higher altitudes, that level of detail in the photographs from a much higher level. Coupled with his innovation of blowing air over the cameras, to stop them condensing, at higher altitudes, it allowed him to take photographs of a much wider area, in every single frame. Unfortunately, once the Second World War would begin, the use of a civilian aircraft over hostile territory would begin to become impossible. As such, he realized a fast modern aircraft would be required to fly high and avoid enemy attention. Cotton played a part in that, he brought to the notice, of the powers that be, the urgent need for a high-speed aircraft for aerial recon.

And his idea moved towards using the Spitfire. He was able to acquire two to be modified with additional fuel tanks and removal of armament. Sidney Cotton's concept was proven when in the first four months of the war, the RAF photographed 2,500 square miles and in doing so lost around 40 aircraft. In the same period, Sidney Cotton's fleet of two Spitfires covered twice that distance - 5,000 square miles and didn't suffer a single loss. The story of Sidney Cotton and the Electra are often full of myths. There is often a mention of three of these cameras facing downwards in the fuselage floor of the Electra. During the restoration at Sywell, the restorers have found only two blanking plates in the underside and no evidence of room to have fitted a third.

The cameras themselves are relatively bulky, so even when mounted facing downwards, they would have protruded above the floor, which also possibly goes against the idea that these cameras were used whilst people were on board not knowing that the photographs were being taken. With the story of the Electra, Sidney Cotton often makes reference to cameras mounted in the leading edge of the wing. During the restoration of the aircraft, evidence was found where cameras could potentially have been mounted. Sidney Cotton, in various accounts, refers to occasions where, with dignitaries on board he overflew installations and pressed a button on the instrument panel with which opened up a window and allowed these cameras to be used whilst flying over these installations.

The issue with this, is that there doesn't appear to have been any evidence of technology to allow those window ports to open, even if the cameras had been fitted. So it was unlikely that the cameras in the leading edge could have been used in such a clandestine way. On occasions, he had rubbed up against authority possibly the wrong way. We saw in the end of the First World War where he resigns his commission due to disagreements with senior officers and something similar happens to him at the start of the Second World War as well, when having proved the concept of photo reconnaissance and the need for faster more capable aircraft, his services are no longer required, when the fledgling photographic unit is absorbed into the mainstream RAF.

While it may be the case that some elements of this story have been exaggerated and embellished, Sidney Cotton and the use of the Electra, his contributions to the development of aerial reconnaissance, are undeniable.

In the years before the Second World War, the Lockheed Electra would have gone relatively unnoticed in the skies of Europe. With its inconspicuous livery it could fly around as much as any airliner would have done in Europe at the time. But while flying over Germany and the rest of Europe, it was able to take photographs. 

The Second World War from 30,000 feet

Visitors looking at aerial reconnaissance photos

As the war progressed, the PRU was equipped with aircraft specifically designed for reconnaissance. The Supermarine Spitfire PR Mk XI was unarmed, with its guns replaced with cameras. It could reach altitudes exceeding 30,000 feet and achieve speeds of over 400mph.
The PR Mk XI photographed the infamous Möhne dam, gathering intelligence on the success of the 1943 Dambusters raid.

The only two remaining airworthy PR Mk XIs, PL965 and PL983, will be displayed in the spotlight exhibition.

Photography Hours

Aircraft assembled for the Spies in the Skies exhibition at IWM Duxford.

To allow better opportunities for photography, between 3pm and 4pm on the following dates the exhibition hall will be fully lit.

  • Friday 2 February
  • Tuesday 6 February
  • Saturday 10 February
  • Sunday 11 February
  • Wednesday 14 February
  • Friday 16 February
  • Saturday 24 February
  • Sunday 25 February


Thank you to the private owners and IWM onsite partners who have helped bring Spies in the Skies: Second World War Aerial Reconnaissance together.

Events and Experiences

Two PR Mk XI Spitfires parked at IWM Duxford
© Liam Shaw
Activities and Experiences

Spies in the Skies: Exhibition Tour

IWM Duxford
Various dates

Photograph of Spitfire N3200, an airworthy combat veteran Spitfire in the Battle of Britain hangar at IWM Duxford
Activities and Experiences, Talks and Tours

In the Cockpit: Spitfire N3200

IWM Duxford
Selected dates

Image of the exhibition title, 'Spies Lies & Deception'
Exhibitions and Installations

Spies, Lies and Deception

IWM London
29 September 2023 to 14 April 2024

Learn More

A collection of Spitfires of various marks
IWM Duxford

The evolution of the Supermarine Spitfire

The Supermarine Spitfire is one of the most iconic aircraft of all time. Between 1932 and 1947 over 20,000 of them were built and in those 7 years, Spitfire's changed dramatically from the Mk 1 to the Mk 24. Graham Rodgers looks at how the Spitfire evolved by taking us through just a few of Duxford's collections.

Consolidated B-24H Liberators of 486th Bombardment Group, US Eighth Air Force, flying over part of the Allied invasion fleet gathered off the Normandy coast, 6 June 1944. They were part of a force of 380 aircraft of 3rd Bombardment Division despatched on the morning of D-Day to bomb villages through which access roads ran to the beachheads.
© IWM EA 25713

7 Amazing Photos of D-Day from the Air

Discover a collection of amazing bird's eye photographs of the fateful day in Normandy.

Wing Commander Guy Gibson with members of his crew, July 1943.
IWM TR 1127
Second World War

The Incredible Story Of The Dambusters Raid

On the night of 16-17 May 1943, Wing Commander Guy Gibson led 617 Squadron of the Royal Air Force on an audacious bombing raid to destroy three dams in the Ruhr valley, the industrial heartland of Germany. The mission was codenamed Operation 'Chastise'.