Everybody knows that there are many rules when it comes to being a member of the royal family. The rules are strictest for people meeting The Queen, which makes sense in fairness. Everyone has to refer to the monarch by her official title. but there was one person who called Queen by her first name except her family which is Nelson Mandela.
Yes, It is well known that former President Nelson Mandela always called Her Majesty by her first name, Elizabeth. When he was corrected, he would look puzzled and say "But she calls me Nelson!".
The South African leader Nelson Mandela famously called the monarch 'Elizabeth' whenever they were together. Mandela enjoyed a “warm friendship” with the Queen, flouting royal custom and was even comfortable enough to comment on Elizabeth II’s weight. On another occasion he said rather candidly: "Oh, Elizabeth, you’ve lost weight."
Also When Mandela lay on his deathbed, Ms Grange visited him as much as Queen could and when his time came she grieved deeply for the man she had once feared.
However, Queen Elizabeth II, who has sat on the English throne since 1952. She joins the ranks of Queen Victoria and Queen Elizabeth I when it comes to long-reigning English female monarchs, though Queen Elizabeth II has outlasted them both. There is something of a tradition in taking a new name when one ascends to the throne. So Elizabeth did the same.