Trevor,
That's an interesting evaluation of the photo. I completely agree that it would not be a photo bY BSA but, just for my amusement, I am going to jump into the discussion and give it my two pence.
I can't really see this as a composite putting together images of two bikes. To match the background so closely, if shot separately, they would most likely need to have been in the studio at the same time and put against the same background. Why bother with separate shots if you have both bikes there at the same time? Then, it's hard to imagine the editor that did such a poor job patching the crease doing such a nice job overlapping the two bikes. Looking at my avitar picture, I don't think you will see where I took out telephone poles and cleaned up around the wheels, and I am a complete amateur. I think some of the shadows have been touched up, added and/or removed. Then, and maybe it's because I am such an amateur, I don't see the difference in shot elevation you've described.
As a side point, why would BSA show cables in the painted advert but not include them in a photo?
Thanks for sprouting the discussion.
Richard L.