Every tartan had a beginning.

Many Scots tartans were simply picked out of Wilson's catalogue and then the mill re-named the tartan after the person who had bought it. Granted, that was in the late 18th century and the 19th, not the 20th or 21st. Quite a few other Scottish clan chiefs chose their tartans only when the King asked to see them in 1822, thinking they all had one (most of them didn't!). Still other Scottish clan Tartans were invented by a pair of English conmen (going as the Sobieski-Stuart brothers, but their real surname was Allen) who wrote an illustrated book and pretended it was a translation of a 17th century work. A few are older than any of the above, but only a very few, perhaps a dozen.

It's all hocus pocus. At least if you know that the Edwards tartan was designed in the 20th century by the Welsh Tartan Centre, then you know more about the origin of it than most Scotsmen do about theirs, and some of the origins of Scots tartans are very murky indeed. Don't let them tell you otherwise.

Us non-Scots have to stick together. The Callaghan tartan was designed in 2007 by Peter Callaghan, who I don't know from Adam, but it is the association with the name that matters, IMHO. There again, it's too bl**dy expensive as well!