This study contributes to research examining how professional autonomy and hierarchy impacts upon the implementation of policy designed to improve the quality of public services delivery through the introduction of new managerial roles. It is based on an empirical examination of a new role for nurses – modern matrons – who are expected by policy-makers to drive organizational change aimed at tackling health care acquired infections (HCAI) in the National Health Service (NHS) within England. First, we show that the changing role of nurses associated with their ongoing professionalization limits the influence of modern matrons over their own ranks in tackling HCAI. Second, the influence of modern matrons over doctors is limited. Third, government policy itself appears inconsistent in its support for the role of modern matrons. The attempts of modern matrons to tackle HCAI appear more effective where infection control activity is situated in professional practice and where modern matrons integrate aspirations for improved infection control within mainstream audit mechanisms in a health care organization.