Oh, that's interesting about the Black Watch. I wonder how much of it was intentional and how much was practical — viz. that if one is looking to have a standard of dress amongst one's soldiers, the most sensible solution is to have them manufactured in the same place, resulting in the same design, instead of simply having the same design replicated (if that makes any sense). With regards to the Cameron tartan, or what Keith thinks is the Cameron tartan, I am willing to explain it away as a regional style, rather than one specifically associated with a clan.