The Royal Family has gathered for its biggest outing since the arrest of Andrew Mountbatten-Windsor . The annual Commonwealth Day today has seen the King and Queen joined for a special service at Westminster Abbey by the Prince and Princess of Wales , Princess Anne and the Duke and Duchess of Gloucester . Ahead of the event, which is one of the major engagements in the royal calendar, Charles issued an annual message to the 56 member nations, which will hold their biennial Commonwealth meeting