As I look at the sample again, it's clear from the fringes on the upper left corner of the sample that there are green threads in both the weft and the warp. However, I see now why I was confused. First, the green is a rather dark gray-green color (unlike the lighter yellow-green that I'm used to from other tartans of the same era) that seems to blend well with the dark blue. Second, and perhaps more important, the threads of the warp appear to be narrower than the threads of the weft, making the weft pattern prominent and the warp pattern subdued, giving an effect like that of a silk tartan.

Other things I noticed: There is a pivot stripe on the selvage, which seems at least a little unusual to me. Also, I was counting the threads in the pivot stripes to see if there was any difference in the warp and weft thread counts. I have to say it's inconclusive, as two of the four pivot stripes are on edges of the cloth. However, I did notice that the red stripe in the weft is seven threads wide—an odd number. Finally, the area where the wide black checks (not sure if that's the right terminology, but they exist on all tartans derived from the Government tartan) cross is noticeably longer in the weft than in the warp. I suspect this observation holds for the entire sett as well.

I haven't tried to do a complete thread count of both the warp and the weft, though, and I'm not sure I want to.