Here are some more photos, where I've tried to show the variation in the main piece of fabric, as well as the different piece of fabric stitched on to form the last few pleats and the under-panel.

There's also some indication that the last few pleats were re-pleated at one point. There are two photos with a blurry finger; one points to a seam, one points to an old crease.

It also looks to me as if the two panels have been taken in to reduce the waist of the kilt.

Again, any obsevations welcome.
Cheers,
John