Britain's Catherine, Duchess of Cambridge, (2R) and her husband Britain's Prince William, Duke of Cambridge (R), arrive with Britain's Prince Harry (C) and his fiancee US actress Meghan Markle to attend a Commonwealth Day Service at Westminster Abbey in central London, on March 12, 2018. Britain's Queen Elizabeth II has been the Head of the Commonwealth throughout her reign. Organised by the Royal Commonwealth Society, the Service is the largest annual inter-faith gathering in the United Kingdom. / AFP PHOTO / Daniel LEAL-OLIVAS