Prior to this he was Director General of Health and Social Services/Chief Executive NHS Wales, a position he had held since June 2014.
Cyn hynny, ef oedd Cyfarwyddwr Arweiniol Adran yr Amgylchedd a Materion Gwledig i Lywodraeth Cymru, ac ar lefel gorfforaethol, ef oedd Pennaeth y Proffesiwn Polisi.