I took a look at your link and it is hard to know what you mean by "this tartan" when all I get is the compete web-site and index.
So I will give you a quick run-down of what I know:
1st observation: the colours as presented on this site are not true to my eye eg. the Sinclair modern hunting is a very dark green in real life not a mid green as presented here, and the ancient hunting is a mid to light green and not much like the one here. No doubt the sett (specific tartan pattern or thread-count) is accurate.
2nd; the two labelled "Sinclair" are large and small sett versions of the same red Sinclair tartan but, again, colours not quite right.
3rd: the one labelled "Sinclair Dress" , overall blue and white, is, from my understanding, a relatively new tartan and was designed and promoted in part by the late Robin Lord Thurso. I have yet to see it worn except by Highland Dancers.
4th the so-called "Sinclair Brown" tartan is barely recognizable to my eye because the colours here are so un-true. It is the one I wear for my day kilt and even I had trouble recognizing it. It is a wonderful soft brown/green and light grey-blue. The source is given as Loch Carron which is correct because they are the ones who invented it about 30 years ago. They call it "Reproduction" and the story (unlikely) given is that a portion of kilt material was recently dug up at Culloden and it was similar to the modern version of MacDonald (or some such) and they decided to extrapolate the colours to various existing tartan setts. I understand they carried this theme into about 50 other standard Clan Tartans. The Thurso family wears this version quite a bit and Stanton Avery, the previous owner of Dunbeath Castle in Caithness, had his staff all outfitted in this tartan.
Hope this is helpful
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