I’m going to assume this is a contemporary costume, because it wasn’t behind glass. But the aesthetic with the stars and the antlers… <3
Museum of London
It’s a Georgian-era fancy dress of Diana (a popular fancy dress costume) with a Yaseman Hussein metal wig commissioned by Philip Treacy, who designed the contemporary hats for the exhibit. There’s a fripperiesandfobs post describing it as a reproduction, but the Vogue article it links to only calls the Pleasure Garden a recreation. Many of the dresses are restored extant garments, so this one might be as well.
"Women speaking of mirrors and prettiness make it all too clear that even for pretty women, mirrors are the foci of anxious, not gratified, narcissism. The woman who knows beyond a doubt that she is beautiful exists aplenty in male novelists’ imaginations; I have yet to find her in women’s books or women’s memoirs or in life. Women spend a lot of time looking in mirrors, but the “compulsion to visualize the self” is a phrase Moers uses of women in her chapter on Gothic freaks and horrors; the compulsion is a constant check on one’s (possible) beauty, not an enjoyment of it."
—Joanna Russ, “Aesthetics,” How to Suppress Women’s Writing (1983).
“At the time, it wasn’t considered ‘normal’ to be gay or lesbian,” [Barrett] said. “Some even saw it as dangerous. But in The Sims it was normal and safe to be a gay person. It was the first time we could play a game and be free to see ourselves represented within. It was a magical moment when my first same-sex Sims coupled kissed. I still sometimes wonder how in the world I got away with it.”