Wrapping the Braveheart kilt

[Calgacus]

Maybe I am misunderstanding your point, but isn't that "doubling" simply the upper half of the plaid, drooping down over the belt before being pulled up to the shoulder??

No, if you look very closely, you can see two parallel edges of the cloth depicted. This indicates a fold of cloth that is two layers thick.

*Edit* Here's the image highlighted in a different way. I have highlighted all the edges in the cloth in BLUE for the outer layer of cloth, and RED for the under layer of cloth.

Grant piper big edges.jpg

You'll have to click on the image to enlarge it and see the highlights. Anything not highlighted is folds, not actual edges of the cloth.