I have finally found publicly available photograph of an extant muslin Robe à l’Anglaise from the Metropolitan Museum all of the examples I’ve seen so far are embroidered so the fact that I’m using a plain fabric is a variation from the documentation but its a variation I can cope with.
While I was searching the met website I found a lot of portraits that could help with my search for a hairstyle I can imitate (Using the advanced search for the years 1760-1799). I just bought a wig on ebay so I can make an attempt at a good 18th century hairstyle.
My stays are now fully boned. I ran out of artificial whalebone as I didn’t allow enough extra for the fact that the boning I’m using is narrower than the pattern recommends so I ended up finishing the centre front panels with cable ties.