Jamie:

The tartan Archie is always seen in (when wearing a kilt) is MacDonald of Donald. His mother Molly and father Hector wear Clanranald.

auld argonian, Hunting Stewart, as you know, is a universal tartan, which I suppose is why they had Duncan wear it. His surname is MacKay. As for that jerk Paul, he was wearing MacDonald of Donald in the episode in question.