Jane Ridley was born in Northumberland, in the northeast of England, the eldest daughter of Nicholas Ridley, a former Cabinet minister, and his wife Clayre Campbell. Her great-grandparents were the architect Edwin Lutyens and his wife Lady Emily Bulwer-Lytton. She was educated at boarding school in Wiltshire, and at the University of Oxford, where she took a first class honours degree in history in 1974. She was a research student at Nuffield College and earned a D. Phil. degree in 1985. In 1979, she was appointed a lecturer in history at the University of Buckingham, where she rose to Professor in 2007.
In 1986, she married Stephen Francis Thomas, a writer, with whom she has two sons. At Buckingham, she is in charge of the Master of Arts course in biography, which she established in 1996. Her first book was The Letters of Edwin Lutyens (1985), a collection of her great-grandfather's letters, edited with her mother. Subsequent works include Fox Hunting: a History (1990), The Young Disraeli (1995), The Architect and his Wife (2002), and Bertie: A Life of Edward VII (2012).