Very interesting.

Now, let me see if I have this right. A Kingussie has a single "convex" box pleat in the centre of the rear, with knife pleats to the right and "mirror" knife pleats to the left. With an optional single concave box pleat on the left just before the apron, which I assume is so that the last pleat before the apron is the right way around. Did I get it right?