The skirt is a folded rectangle with an elasticised waistband on one side at the top and a space for legs on the other side, at the bottom.
I'm yet to work out the formula for the size of rectangle in relation to the size of person it is to fit. With this one, I got the length of knitting a bit wrong (the rectangle was too long) and had to tuck up the bottom a bit and stitch it into place.... Anyone at least 3 inches taller than I am (and that would be most of you) wouldn't have to do this.
The top is one featured in Le Book.