Gough (in ‘Britannia’, above) describes the horse as 100 feet long and 100 feet from eartip to toe – but this is nothing like he drew it (see the link for the strangely distorted animal) – you can tell that he drew it from above the horse because its body is much bigger than its legs... I think we can conclude that it’s bloody difficult to draw an upside down horse whilst allowing for massive foreshortening. I’m even inclined to think this could also account for the wavy tail and that it’s facing the opposite way to today’s reality. The HFH charitably suggests that a printer error might have reversed the image.
(I’ve seen quite a few versions of this Gough drawing – I’d like to know which is the Real One!)