Identifying odd tartan

[Downix]

I tend to agree with Matt's first instinct on this one even though it's showing up a bit dark on my screen as well. The lone field of red in the upper right quandrant of the OP's picture is much smaller than the typical field of red in Royal Stewart. I'd call it PCE Stuart Modern. 2 examples of PCE Stuart from 2 different mills and the original pic:

Better sample picture:

Yes, it looks very similar to the top one. So much so I'd suspect that the slight difference has to do with dyes used.

Pity the selvage is so poor, it looks amateurish. I suppose I could hem it up to make it work.