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 state dinner March 14, 2012 in Washington, DC.

*At Wednesday night’s White House state dinner for British Prime Minister David Cameron and his wife Samantha, Michelle Obama wore a dress from a fashion house co-owned by one of the guests at the event.

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.

Whoops. President Barack Obama (C) accidentially steps on First lady Michelle Obama's dress as they walk onto the North Portico

Mrs. Obama’s jewelry is by Tom Binns, a Belfast-born designer who is also headquartered in New York.

Meanwhile, Samantha Cameron is wearing a dress by British designer Alessandra Rich.