The third link I gave touches on this, although doesn’t specifically say it: The whole photograph (about halfway down the page) shows the far shore of the loch. From this, the angle of view could be determined, and therefore the distance to the object calculated, and therefore its height. The portion of the monster poking out of the water turned out to be only a foot high. The fact that Wetherall knew about this “uncropped” version of the photo, when all the newspapers ever since have carried the cropped version, is further evidence that he was in on it.