How was Peter D. Mitchell awarded the Noble Prize?

Name: Peter D. Mitchell. 
Country: England.
Date of Birth: 29 September 1920.
Date of Death: 10 April 1992.
The subject of Study: Adenosine diphosphate, chemiosmotic theory.
Noble Prize Year: Nobel Prize for Chemistry in 1978 for their research theory of the chemiosmotic mechanism of ATP synthesis.