I've been busy and could not work on this gown until now.
Since drafting the pattern I've come to the conclusion it is much easier to work with the Janet Arnold pattern instead of the Norah Waugh version.
I've used the back and side back pieces from The Elegant Lady's pattern, and the rest is drafted up to match.
The pattern is missing the front piece at the moment as I ran out of interfacing. It is basically pieces of fabric joined together at the seams.
Pleats pinned into place using the illustration in Janet Arnold as a guide.
Pinned to my dummy. The interfacing is very awkward. Looking forward to using some real fabric soon.