One of the best things about auction sites (when compared to museum sites) is that you get far more images of the objects, and often from unusual but helpful angles. This is true for furniture– good auction sites will post photographs of the undersides of sofas and desks, a level of detail museums simply lack the time for. For clothing, construction details aren’t always noted in the record, so we rely on images. This is where the auction sites can really be a boon: turn me round, baby.
I don’t know if I’d go as far as “boned corset” (well, I wouldn’t) but the boned bodice provides a lot of interior structure to this gown. The box pleats give the brocade skirt structure and fullness, but rely on the petticoat for the full silhouette. The interior structure probably didn’t provide enough support to allow the dress to be worn without additional undergarments– bra, panty girdle, even another petticoat– though it’s hard to say without knowing the original owner and feeling the dress. (Think of the boned bodices in late 19th century bodices: we know those weren’t enough to create the proper silhouette.)
It’s a wonderful look at the interior of a vintage dress, though, and one that makes replicating this garment (and look) so much easier.