Okay, so the previous article and the analysis of the photograph's EXIF data led me to conclude this was not a photograph of the Loch Ness Monster. I continued to talk to Steve, the photographer, but that has come to an end as he could not provide the original SD card image. But I was looking for something objective and not just opinions that would seal the deal on this one and it came from Jeriah Houghton who found the above image of a catfish at this site.
As you can see, the spots on the catfish all line up nicely with the spots on our Nessie. So it is beyond doubt that this catfish photo was cut and superimposed on an empty shot of the loch with the colour of the catfish portion being altered in colour. So, nice work, Jeriah!
There is also a nice animated GIF made by "rewyndwilliams" which is here and reproduced below showing the two images sequentially overlaid. The case is closed but I will write a follow up article on photoshopped images as I feel there are some deficiencies in how we approach this subject.
The author can be contacted at firstname.lastname@example.org