Born in Shanghai, China, she was the daughter of Stanley Morris Thornley, the British Ambassador to China. Sandra Thornley returned to England during the expulsion of foreign nationals that occurred during the Communist Revolution. She afterwards attended the Arnold High School for Girls in Blackpool and was married in 1960. At the age of 28 she enrolled on her first degree course while she was a single mother at the University of Manchester (as a mature student) and took a first class BA degree in Politics and Modern History. Following this she became a lecturer at Manchester Polytechnic and rose gradually to be Deputy Vice-Chancellor and Academic Director by 1992.