It was said to be one of the best photos of a UFO, and a poster-size image of it hung on a wall of Britain's Ministry of Defence. But then, at some point between 1991 to 1994, it vanished, gone, never to be seen again.
On the day in 1991 that Nick Pope interviewed for the position of chief of the Ministry of Defence's UFO office, he could not help but notice the UFO image on the wall. "I went in for an informal interview, and anyone sitting in that office found their eyes drawn to that image," Pope told The Huffington Post.
Other original pictures, negatives and the wall poster somehow vanished in the 1990s. Only a Ministry of Defence line drawing remains.
The photo was one of six taken by a pair of hikers who spotted a strange diamond-shaped object in the sky over Pitlochry, Scotland, on Aug. 4, 1990. It appeared to hover in the air near an Royal Air Force Harrier jet. Eyewitnesses reported seeing the unusual object above the ground for nearly 10 minutes before it zoomed away at high speed.
The 1990 incident was described in a batch of previously classified UFO files released by the Ministry of Defence in 2009.
Pope told The Huffington Post that it was the ministry's official policy to obtain as much information as possible in the case of a UFO sighting, such as photo negatives. The pair with the photos contacted the staff of a newspaper that planned an article; the newspaper, in turn, reached out to the Ministry of Defence for additional information, Pope said. That's when the ministry requested and obtained the original photographs and negatives from the newspaper, he said. "From everything I know about the defense intelligence staff, they would have done that."
The incident took place just before Pope took over the ministry's UFO division in 1991 to 1994. When he started his job, Pope couldn't help staring at the enlarged image of the UFO on his office wall.
"It looked like a diamond on its side; it was three-dimensional, meaning it had some depth to it," Pope recalled. "It was a dull, metallic gray color. But the most disconcerting thing about this was [that] despite its large size -- over 80 feet in diameter -- there was an apparent lack of any real aircraft-like structure to it.
Watch this National Geographic report about the disappearance of the UFO photos in Scotland:
"Moreover, there was no apparent propulsion system and no markings," Pope added. "This made us think that whatever it was, it clearly was a technology significantly ahead of anything we had in our inventory or even on the drawing board."
Pope described another reason for interest in the object: "There was no apparent sound from the craft, especially with it being within a couple hundred feet of the eyewitnesses."
"Naturally, we wanted the propulsion system," he added. "And if we couldn't get it, we wanted to at least try and understand the principles on which it might work because that might play into research and development."
"This wasn't the archetypal distant, blurred UFO photo," Pope added. "This was up close and personal, reach-out and you-can-touch-it stuff. 'I don't know what it is, but it's not one of ours' was the stock answer to the inevitable question. Word got around and people would swing by to take a look, even when they had no obvious business in our section."
According to Pope, his superior officer was convinced that the object in the UFO photo was a secret, prototype aircraft from America. But after assurances from U.S. authorities that they weren't testing anything like that over the United Kingdom, Pope's boss took the poster down and locked it away somewhere.
"The original photos were sent to the defense intelligence staff, who then sent them on to imagery analysts at the Joint Air Reconnaissance Intelligence Center," said Pope, at right. "At the time, [the Ministry of Defence] hadn't even publicly acknowledged that there was any intelligence interest in UFOs. Though we'd never say so publicly, the bottom line was that we wanted the technology. It was better than anything we had and we wanted it for our own military aircraft and drones."
"I would not put myself in the [UFO] believer camp," Pope said. "But if I was going to end up there, this case, in terms of evidence, would give me a big push in that direction."
Why does this UFO story continue to surface every few years? Because like the legendary tales of the Roswell, N.M., UFO crash of 1947 or the infamous top-secret world of Area 51 in the Nevada desert, some mysteries are not easily put to rest.
With eyewitness accounts, high-level government interest and the sudden disappearance of the visual forms of evidence (the photos and negatives), the 1990 incident has all the ingredients that UFO legends are made of.
Most UFOs can be easily explained. Check out these scenarios:
These candle-lit Chinese lanterns can rise high into the sky and are often mistaken for UFOs.
This is a composite image of how three alleged UFOs maneuvered about in the sky over Melbourne, Australia, in early February, 2013. The final verdict isn't in yet on whether they're birds, aircraft, balloons, bugs or something truly unidentified.
On Dec. 20, 2012, a bright, circular object (pictured at the top of this composite image) was videotaped exploding in the skies above Sacramento, Calif. It wasn't immediately identified, resulting in speculation that it was either an alien spacecraft, military top secret weapon, runaway planet, North Korean satellite, among others. Within a short period of time, it became apparent that this was a weather balloon. The bottom part of this image shows such a balloon as it ascended over Tampa Bay, Fla., on July 2, 2012, and exploded in an identical manner as the Sacramento object, probably much to the dismay of all true ET believers out there.
This is a composite of images shot by two eyewitnesses of a boomerang-shaped UFO they reported seeing over their Burbank, Calif., home on Oct. 5, 2012. Mutual UFO Network photo/video analyst Marc Dantonio concluded the object was likely "a balloon, floating on the wind that has collapsed in half."
This four-image series of lights in the sky was recorded over Warren, Mich., on Jan. 10, 2013. The lights were seen changing into several patterns. The most logical explanation for these types of UFOs is a series of balloons or lanterns.
This composite image shows four different times that alleged UFO were photographed above Earth by either space shuttles or the International Space Station. The big question is whether or not they are truly unidentified objects or if they are more likely reflections from spacecraft windows, meteors or fast-moving spacecraft-generated debris.
What appear to be pink-red UFOs are actually lens flares from the Google Earth street view camera as it snapped images in Texas (left) and New Mexico (right).
These two flying saucer-shaped, pink-colored lens flares were created by the Google Maps camera as it drove through locations in Sedona, Ariz. (left) and Flagstaff, Ariz. (right). The images were snapped in April 2009. Submitted to HuffPost by trenna.
This skybound lens flare was created by a Google Maps camera in June 2008 over Whiteriver, Ariz. Submitted to Huffington Post by Cheryl Weeks.
This very Earthbound lens flare was created by a Google Maps camera in November 2007 at Gulfport, Miss. Submitted to Huffington Post by Jenni Parker.
This seemingly grounded lens flare was created by a Google Maps camera in January 2008 at Eureka Springs, Ark. Submitted to Huffington Post by SE.
This lens flare appears to be following a car. The Google Maps image was created in October 2008 at Escanaba, Mich. Submitted to Huffington Post by Mary Robinson.
On the night of Sept. 28, 2012, a group of strange-looking lights appeared in the sky near Cincinnati, Ohio. First there was one, then, two, then three lights, slowly descending. It turns out, however, that these lights were originating from a group of skydivers performing a pyrotechnics jump at the La Salle High School homecoming event.
Some UFO sightings may be due to a natural phenomenon known as sprites, like this one shown from 2006. "Lightning from [a] thunderstorm excites the electric field above, producing a flash of light called a sprite," said geophysicist Colin Price.
Clouds: Saucer-shaped or "lenticular" clouds that form at high altitudes have been confused with UFOs.
Blimps or advertising balloons: These can look like flying saucers from some angles, especially at night.
On June 19th the Swedish-based diving company Ocean Explorer discovered something they've never quite seen before. They were exploring in the Baltic Sea between Sweden and Finland looking for sunken treasures when a very unusual image suddenly appeared on the sonar. A 197 feet diameter cylinder shaped object was discovered at the depth of approximately 275 feet which resembles the Millennium Falcon from the movie Star Wars.
An image released on June 15, 2012, shows a close-up view of the unidentified object sitting on the bottom of the Baltic Sea.
Close-up of rock bed that forms the Baltic Sea UFO, which still mystifies researchers.
One of several odd stone circle formations, sitting on top of the unidentified object at the bottom of the Baltic Sea.
A circular UFO hovers above the Neumayer-Station III research facility in Antarctica on Aug. 10, 2012. Theories ranging from a simple weather balloon to a more elaborate ship from another planet have run the Internet gamut. The next slide shows a closeup of the object.
This is a closeup of the UFO from the previous slide. No official explanation has been offered about the object.
Pictured is a quad copter -- a deliberately manufactured UFO created by special effects wizard Marc Dantonio for a National Geographic special, "The Truth Behind: UFOs," which aired in December 2011. On the left is what the small device looks like resting on the ground, measuring 4 feet in circumference. At right, is how it appeared behind a tree in the night sky.
In February of 2012, this fireball was captured by a Texas police chief's A dashboard camera. F.A.A. say this was probably a meteor, falling to Earth. .
Meteors: Space debris can create a spectacular light show when it burns through the Earth's atmosphere, and sometimes reported as UFOs.
Civilian or military aircraft: Planes can look mysterious at night or in certain light conditions, thus confusing an observer.
CORRECTION: In a previous version of this story, we had the word "infantry" instead of the correct "inventory," which now appears.