Simplify the following text for a Grade 7 native English-speaking person.
Original: Sargent was chief conductor of the Proms from 1948 until his death in 1967 and of the BBC Symphony Orchestra from 1950 to 1957 , succeeding Sir Adrian Boult .
Simplified: Sargent was chief conductor of the Proms from 1948 until his death in 1967 . In 1950 he followed Sir Adrian Boult as conductor of the BBC Symphony Orchestra .