This is actually a launch party for Sienna Miller’s sister’s clothing line, but this look could also do double duty as a costume for her in a 70s movie About Romantical Trials and Tribulations of women working in a munitions factory during the war. (Sienna’s dashing fly boy pilot lover will not, I am sorry to tell you, make it out alive. But her character is very resilient. It’s going to be sad, but she’ll be okay.) It’s almost period but they couldn’t bring themselves to do the hair and makeup. Regardless of time period: This is super cute. Let’s all go run around in wide-legged pants together!