The use and meaning of the term 'cotter pin' is obviously varied as the split pin meaning is either the first meaning or the second depending on which dictionary one uses. I did look the term up in a number of on-line sources and found views that either back up, or counter my point of view.
I don't doubt you can get stainless to a reasonable grade (but lots are not), and John Worrall is probably the best source for something like this where I'd not be too sure of many suppliers. However, the front wheel bearings on a Morgan are fully enclosed, the castellated nut and washer the pin fits into are a normal steel, and since the split pin is a single use device, rather pointless spending extra money on it as it's a hidden component, and won't ever go rusty.
Oh well, à chacun son goût.
