In 1965, the Duke and Duchess visited London as the Duke required eye surgery for a detached retina; Queen Elizabeth II and Princess Marina, Duchess of Kent, visited them. The Duke's sister, the Princess Royal, also visited just 10 days before her death. They attended her memorial service in Westminster Abbey. Later, in 1967, the Duke and Duchess joined the royal family in London for the unveiling of a plaque by Elizabeth II to commemorate the centenary of Queen Mary's birth. Both Queen Elizabeth II and Prince Charles visited the Windsors in Paris in the Duke's later years, the Queen's visit coming only shortly before the Duke died.