Simplify the following text for a Grade 12 native English-speaking person.
Original: For example , the British Ambassador to the United States , Sir David Manning , was appointed a CMG when he worked for the British Foreign and Commonwealth Office ( FCO ) , and then after his appointment as British Ambassador to the United States , he was promoted to a Knight Commander ( KCMG ) .
Simplified: For example , the British Ambassador to the United States , Sir David Manning , was appointed a CMG when he worked for the British Foreign and Commonwealth Office ( FCO ) .