The UK sovereign is usually addressed as `` His/Her/Your Majesty '' , but may also be called `` His/Her/Your Royal Highness '' and `` His/Her/Your Grace '' .
`` In the United Kingdom , whose monarchy is a purely statutory institution , only the style Royal Highness has been used since 1917 , and its use is restricted by law to the sovereign ( who is normally addressed `` '' His/Her/Your Majesty '' '' but may also be called `` '' His/Her/Your Royal Highness '' '' and `` '' His/Her/Your Grace '' '' ) , the children of the sovereign , and the children of the sovereign 's sons - but not the children of the sovereign 's daughters.  ''