Mm, well, that would depend upon when you go from them actually being nations. England didn't become England until long after the Romans had buggered off. I worked my age order out from history and guesswork on the part of historians and they have about 200 years between each of them (ie Scotland is 200 years older than England, Ireland is 200 years older than Scotland, etc).

Why Cornwall, though? It's just a county. o.o