Worsley began her career as an historic house curator at Milton Manor, near Abingdon, in the summer of 1995. From 1996 to 2002, she was an Inspector of Historic Buildings for English Heritage in the East Midlands region. During that time she studied the life of william Cavendish, 1st Duke of Newcastle and wrote the English Heritage guide to his home, Bolsover Castle. In 2001 she was awarded a DPhil degree from the University of Sussex for a thesis on The Architectural Patronage of william Cavendish, first Duke of Newcastle, 1593–1676. The thesis was later developed into Worsley's book Cavalier: A Tale of Chivalry, Passion and Great Houses.