Princess Beatrice has stepped in for Prince William at a key event, as the Prince of Wales supported King Charles in the absence of Princess Kate and Princess Anne. On Tuesday, Prince William attended events during the Japanese State Visit, including a carriage ride down The Mall and a State Banquet at Buckingham Palace in the evening. The Emperor and Empress of Japan are visiting the UK at the invitation of King Charles and Queen Camilla. As a result, the Prince of Wales, 42, could not attend the Earthshot Prize Water Roundtable, which was held on the same day. William, who founded the Earths…