Simplify the following text for a Grade 7 native English-speaking person.
Original: George VI remained as King of Pakistan until his death in 1952 and his successor Elizabeth II was Queen of Pakistan until Pakistan became a republic on 23 March 1956 .
Simplified: George VI remained as King of the United Kingdom and King of Pakistan until his death in 1952 . Pakistan became a republic on 23 March 1956 , so Elizabeth II was Queen of Pakistan for four years .