Kate Middleton and Prince William reportedly attended the 50th birthday party that Pippa Middleton threw for her husband, James Matthews. Kate Middleton and Prince William partied so hard they got noise complaints. The couple attended the party Pippa Middleton threw for her billionaire husband James Matthews' 50th birthday last Saturday, and apparently their neighbors were not here for it. Truly, nothing says 50th birthday like a "silent disco!" Anyway, pics of William and Kate at the event haven't been leaked just yet, so tbd on what their interpretation of the "racy" theme was.