Simplify the following text for a Grade 7 native English-speaking person.
Original: Sir John Grey Gorton , GCMG , AC , CH ( 9 September 1911 - 19 May 2002 ) , Australian politician , was the 19th Prime Minister of Australia .
Simplified: Sir John Grey Gorton ( 9 September 1911 â `` 19 May 2002 ) was the 19th Prime Minister of Australia .