(L-R) Britain's Camilla, Duchess of Cornwall, US actress Meghan Markle, Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge 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 / POOL / Paul Grover