To celebrate Princess Charlotte's ninth birthday on Thursday, 2 May, the Prince and Princess of Wales released a beautiful new picture of their daughter which was taken by her mum.The photograph shows the little Princess posing outdoors in a navy blue jumper, maroon cardigan and denim skirt. Alongside the image which was shared on the couple's social media, a caption read: "Happy 9th Birthday, Princess Charlotte! Thank you for all of the kind messages today." While fans rushed to show their love for the birthday girl and point out how much she has grown since she was last seen in public on Christmas Day, there was something else they were quick to notice.