Was Nelson Mandela knighted as a 'Sir'?

Answer 1

Nelson Mandela is an honorary British knight (as of 1995). As such he is not entitled to be called Sir.

An honorary award is one made to a person who is not a citizen of a Commonwealth realm. They cannot use the pre-nominal style of 'Sir' or 'Dame', but can use the post-nominal letters (after their names) subject to the prevailing conventions in their own country. If such a person later acquires citizenship of a Commonwealth realm, then any honorary awards are usually made substantive and, in the case of knights and dames, they can begin to use the pre-nominal styles.

Nelson Mandel has received Knights Grand Cross of the Royal Norwegian Order of St. Olav and The Order of the Elephant (Danish: Elefantordenen) (the highest order of Denmark. It has existed since 1693, and is almost exclusively bestowed on royalty and heads of state.)