And then there's one more thing that's always bothered me about the Calvine photograph—the angle of the "fighter jet." It just happens to be at the exact angle we would expect if it were a small plastic model floating on the surface of the water...
...Wouldn't that depend on what angle we were viewing it from? I don't think there's an exact angle that would indicate it's a reflection.
If our eyeline was just above water level, we would see (assuming the model was floating more or less evenly, tailfin pointing roughly upwards) the side, or the top half of one side of the aircraft- and presumably its reflection underneath, something very roughly like this:
I'm imagining that as we increase the height of our POV, we would gradually see more of the top surface, the tailfin would be foreshortened and the starboard wing would start coming into view, as if it were a real aircraft seen (from the same horizontal plane) banking.
With a plan view of a floating plane model, we would see whatever top surface was visible above water.
So I don't think the possible jet/ model jet/ whatever it is, is being viewed at a specific angle, or is at a specific angle, that supports a reflection hypothesis.
If the water is sufficiently still to enable a fairly good reflection of a modest rock, intuitively I feel that the "jet" (as seen in the Calvine photo) should be more symmetrical than it is, if it too is an object on the water's surface.
If this is a hoax using a reflection with a floating "jet", the hoaxer has to place it on the water, wade back (maybe only a very short distance) and wait for the ripples to subside.
I made loads of plastic aircraft models as a kid; don't recall trying to float any of them but I remember the Harrier kits often had "posable" jet nozzles on each side, so small boys (and girls) could angle them pointing down or rearwards, so I guess water would soon leak into the fuselage. Other plane models might not have this problem, but I doubt they were designed for buoyancy! Not a major problem for a committed hoaxer though, and we have "the surgeon's photo" of the Loch Ness Monster, a model dinosaur mounted on a (clockwork ?) 'functioning' toy submarine.
Another possible issue with a floating model hypothesis is the second "Harrier" reported by UK Ministry of Defence examiners in one of the other photos (which we don't have). No reason that hoaxers couldn't build two floatable models, but then why claim to have seen only
one jet when they've deliberately spent time composing a scene with two?
(A quick aside re. the different brightness of the "jet's" "wings": Not all aircraft have wings that are in the same horizontal plane; Harrier wings have a marked downward angle
...so the apparent brightness of the wings can differ from each other depending on the position of e.g. the sun/ the observer relative to the aircraft; below Kestrel prototype, Harrier, Harrier II):