After graduating and receiving her PhD, Thorne undertook a year-long research fellowship at Harvard University, where she worked with Professor Norman Ramsey.
In 1955, Thorne joined Imperial College as an assistant lecturer in the Physics department. She was promoted to lecturer in Physics in 1956 and again in 1968 to senior lecturer. During her time at Imperial College, she was first person to take up the role of senior tutor for women students and successfully argued for the implementation of the Day Nursery, which opened in 1970.
In the 1970s, Thorne worked on vacuum-ultraviolet interferometry and oscillator strengths by Mach–Zehnder interferometry, and in 1974, she published the academic text book Spectrophysics, which was subsequently rewritten as Spectrophysics: Principles and Applications in 1999.
During her tenure at Imperial, Thorne's main non-scientific voluntary work was to improve education. She served on the Governing Boards of 8 different schools and Colleges, both State and Independent. She was the Chairman of Governors of Ardingly College for 5 years.