TONGA - FEBRUARY 01: Queen Elizabeth II and Prince Philip, Duke of Edinburgh entertain King Taufa'ahau Tupou IV and Queen Halaevalu Mata'aho 'Ahome'e of Tonga on the Royal Yacht Britannia on February 01, 1977 in Tonga. (Photo by Anwar Hussein/Getty Images)

TONGA  - FEBRUARY 01:  Queen Elizabeth II and Prince Philip, Duke of Edinburgh entertain King Taufa'ahau Tupou IV and Queen Halaevalu Mata'aho 'Ahome'e of Tonga on the Royal Yacht Britannia on February 01, 1977 in Tonga. (Photo by Anwar Hussein/Getty Images)