In order: Samantha Cameron, First Lady Michelle Obama, British Prime Minister David Cameron, and U.S. President Barack Obama pose for photographs on the North Portico of the White House before attending a sate dinner March 14, 2012 in Washington, DC. 
The frock is designed by New York-based label Marchesa, whose co-founder is Georgina Chapman, the British-born wife of Hollywood producer Harvey Weinstein — and a guest at Wednesday’s dinner.
Meanwhile, Samantha Cameron is wearing a dress by British designer Alessandra Rich.
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