Happy Mother's Day to all the U.K. mommas out there, including Kate Middleton! The Duke and Duchess of Cambridge marked the holiday on Sunday, March 22 by treating us all to a carousel of delightful family photos on social media. "To mothers new and old and families spending today together and apart – we are thinking of you all at this difficult time," the royal couple wrote on their official account. "Happy Mother’s Day." Their greeting circulated with a lovely collection of pictures - including a never-before-seen Cambridge candid! Scroll through to see them all.