I’m only semi-surprised that the Daily Mail has fallen for this semi-regular silliness, inter alia:
The first trains, in the 19th century, were made to the same width as horse-drawn wagons, which were, in turn, built to fit in the ruts left in the roads by the chariots of the Roman invaders two millennia ago. The British standard rail gauge of 4ft 8½ inches is based on the specification for an Imperial Roman war chariot. Why the precise width? Well, the Romans calculated it as the average size of the backside of a horse. The problem is that that the bum-size of modern travellers is creeping ever closer to that of our equine friends, posing a growing nightmare for air travellers, too.
As might be expected, this is one which rogueclassicism has dealt with before: