 Upon graduation, she took up a position with the Middlesex Hospital London as a Postdoctoral Research Fellow in the Courtnauld Institute of Biochemistry.Halliday returned to Australia in 1956 and lectured in biochemistry with the Department of Pathology of the University of Queensland, researching lead poisoning and haematological problems.University policy at the time would not permit her to work full-time after the birth of her first child.