Alas, I can only provide you with a link since I don’t have time to actually steal the content.
As was the custom of late Victorian and Edwardian genre painters, Talbot Hughes had amassed an extensive collection of historical costumes and accessories as studio props dating from the 16th century through the 1870s. The collection was donated to the Victoria and Albert Museum after it had been exhibited at Harrods department store in 1913. Samples of Hughes’s costume collection remain on public view at the V&A to this day in the British Galleries
Basically, in 1913, a bunch of folks put on these gowns and they took pictures of them. Scroll down a bit to reach the Regency gowns.
And, just because I’m nice, here’s the Wikipedia entry for the Victoria and Albert museum, which is a pretty huge time suck. You’re welcome. You should be glad I’m not linking to the V&A because then you’d NEVER get free. Oh wait, I’m not that nice. Victoria&Albert Museum.