Anyway, that 9th Century Scotland? It was full of 'English' Anglo-Saxons. The Kingdom of Northumbria stretched all the way up through the borders to Lothian. 'Scots', as in the dialect, is one of the descendent of the Old English spoken by Ye Olde Northumbrians (along with Northern English dialects).

It's all a bit of nonsense whinging about what's 'celtic' and what's 'English' in this context, whether it's an animated fantasy or historical reality.