London, UNITED KINGDOM - **FILE PHOTOS** Prince Louis celebrates his sixth birthday with his parents Prince William of Wales and Catherine Princess of Wales, Kate Middleton, and his siblings Prince George and Princess Charlotte in the UK. Louis is one of the grandchildren of King Charles III and is fourth in the line of succession to the British throne behind his father and siblings. *UK Clients - Pictures Containing Children Please Pixelate Face Prior To Publication*,Image: 867106992, License: Rights-managed, Restrictions: RIGHTS: WORLDWIDE EXCEPT IN GERMANY, NETHERLANDS, Model Release: no, Pictured: Prince Louis, Credit line: BACKGRID / Backgrid USA / Profimedia