As to the suggestion that "...unless a tartan is registered with the Lyon there is NO legal status accorded to it," I would suggest that one could take the view that an unregistered tartan is no different than an unregistered motorcar. A lack of registration does not, in itself, necessarily imply a lack of ownership.
Um, I wouldn't take it that far. You're mixing two subjects: physical property and intellectual property.

Physical property needn't be "registered" in order to be legally owned. Intellectual property, however, usually does. That's what trademarks, copyrights, and even (in a lesser sense) the registering of tartans are for.

That minor point aside, I do think it's an interesting subject and I'd love to see more on this pending case which you mentioned very vaguely.