Also, I took the opportunity while it was still held taut, to do some darning in. There were warps tied off at pins to create shaping in various places.
I untied them and darned one end downward and one end upward.
Then as I gradually unpicked the holding stitches around the hem...
I darned in warps and drew up slack where needed.
Then the edge was even.
With the hem free, I could turn back the overpockets to reveal the underpockets...
and I took out the pins holding them in place.