I would suggest that we are overthinking this issue a bit. What we have here is not a case of two different tartans recorded with the STA, but the same single tartan recorded twice, under two different names.

Without talking with Brian Wilton (STA Director) I can only guess why, but my assumption would be so that there would be an entry both under the name US Marine Corps and Leatherneck, in order to make the tartan more easily found in the search engines.

Indeed, just from looking at the numbers of the tartans, I can tell you that No. 975 was added early on in the original Scottish Tartan Society database, and No. 3612 would have been added much later by the Scottish Tartans Authority (the old STS database never got that high in numbers).

I note that it is the latter tartan that is called "Leatherneck" and that record was most likely added because of the frequency of which the USMC tartan is called by that name. They would have wanted it to be found under "Leatherneck" if anyone went looking for it.

Why there is a slight color difference is anyone's guess. My theory would be that when the second record was created they were going off of an actual woven sample. Certainly the software they were using to input the record at the time would have allowed whomever entered the data a wider range of color options. If memory serves, the original STS software was fairly limited in those terms.

But as has been pointed out, the thread counts are exactly the same in both cases. And the STA does not go about recording every minor color variation of each tartan, otherwise there would need to be a different entry for the modern, ancient, muted, weathered, etc., from each of the woolen mills, as they each have their own different color palette they use, etc. It would be a nightmare.

The color difference in the two samples Steve posted can simply be chalked up to the fact that the samples were woven by two different mills. This would be true of most any tartan.

The same can be said about the slight variation in width on some of the stripes. This happens more often than one might think. For example, here are two samples of the ancient Armstrong tartan, one woven by Lochcarron, the other by House of Edgar.



Note the difference in widths of the wide black stripe. Why would mills do this? I suggest it is not a matter of "poor quality control" but may in fact be something done intentionally in order to distinguish their product from another company's. Why would someone choose tartan woven by one mill over another? Perhaps they like that mill's colors better? Perhaps they like the way that mill laid out the proportions of the tartan better? If every mill wove every tartan identically, there could be no competition between them.

And remember that the thread counts recorded for tartans are not absolute. They are to give an indication of the pattern and the general proportions. I don't think any observer would have a problem looking at both samples that Steve posted pictures of and identifying them as the Leatherneck tartan, despite the minor color differences and the different widths of the red stripes.

So let's not loose too much sleep over this, shall we? :-)