It was a royal affair in Northumberland, England, on Saturday as the Duke of Northumberland's youngest daughter, Lady Melissa Percy, married Thomas van Straubenzee at St. Michael's Church at Alnwick Castle. Princes William and Harry wore their finest for the affair, after getting the celebrations started during a night out with the groom-to-be in London earlier this month. Kate Middleton did not attend since she's currently on maternity leave, awaiting the arrival of her first child, but her sister, Pippa, was among the guests, which also included Sir Richard Branson's daughter Holly and Princess Eugenie. Prince Harry's ex-girlfriend Chelsy Davy was part of the wedding party, and she and Prince William shared a laugh together during the festivities. Harry's current flame, Cressida Bonas, was also in attendance, though she wasn't photographed with him at the event.