Origins of septs.....

[Micric]

I think Jock got it right, at the start of this thread.......a way of selling more tartan.

Sept I gather is an irish word, meaning 'clan' or family.

It was just 'borrowed' to add names to the clans, thereby opening the market for more cloth.
Yes, there are at times bona-fide connections with clan and other names, and many carry Clan blood, but this has nothing to do with the term 'Sept".

Does "Sept" sell more tartan?
You can bet your woolie socks it does!
I've stood in Moffat weavers shop, and watched people deperately, even forlornly, scanning the "sept' lists, hoping against hope to find Some connection, to Some tartan .....To Any tartan! If the Septs were enlarged to cover more names, I don't think many would argue. :-)