Prince William has been photographed sharing a sweet moment with his kids Prince George and Princess Charlotte at the Run Sandringham half marathon event.The Duke of Cambridge, who is celebrating his 39th birthday today, was seen wearing a blue shirt with dark trousers while his son George, seven, looked his spitting image in a checked shirt and blue shorts. George's six year old sister Charlotte looked adorable in a pale pink jumper with a shirt underneath alongside some blue shorts.