Much of his research concerns the automated generation of efficient, systematic test suites on the basis of program code, models or specifications. He has a particular interest in testing based on state-based models, typically expressed either as a form of state-machine [14,18] or using a process algebra such as CSP [15,16]. He has a long-standing interest in mutation testing [20] and search-based software testing [17, 19] and has contributed to the formal, fault-based testing of stochastic and probabilistic systems [21-23]. At Sheffield, he is the Departmental Director for Research and Innovation. Hierons was joint Editor of the Journal of Software Testing, Verification, and Reliability (2011-2022) and is a member of the editorial board of Formal Aspects of Computing. He has been the programme co-chair of several internal conferences and will be programme co-chair of ICSE NIER 2024.