This isn't a complete answer, but I think I can add to the plausibility of it being a real photo by explaining the lighting.

During an eclipse, the Moon casts a shadow on the ground. Concorde 001 is depicted at the "diamond ring" point of an eclipse, where the Sun is just barely touching the edge of the Moon's disk. Therefore the aircraft, while still in shadow, is only on the very edge of the dark area. Looking out from the windows of an aircraft at altitude, the view of the ground would appear like this:

As you can see, although there is very little light from the Sun, there is quite a bit of light reflected back from the illuminated part of the ground. I believe this reflected light is what's illuminating the aircraft. (Note that in the original version of the Concorde image, the light has quite a strong blue cast, which is consistent with this as well.)

Additionally, one of the answers mentions "light rays appearing to pass between the plane and the viewer". I believe that these "light rays" are simply a lens flare or diffraction effect, caused by shooting directly into the small area of the Sun that's visible on the edge of the Moon's disk.

Note that the lighting provides further evidence that the photo was taken from another aircraft. They would have to have been flying at quite a high altitude for the lighting to look like this.