Rhwng 2008 a 2015, Keith oedd Comisiynydd Plant Cymru. Mae'n arbenigwr uchel ei barch ar hawliau plant ac mae ganddo fwy na 30 mlynedd o brofiad mewn gwaith cymdeithasol, gwaith ieuenctid a rolau mewn gweinyddu cyfiawnder. Roedd Keith yn aelod o Fforwm Diogelu Plant Cenedlaethol Llywodraeth Cymru ac yn aelod panel o'r Adolygiad Cyfiawnder Teuluol.
Keith was the children’s commissioner for Wales between 2008 and 2015. A respected children’s rights expert, he has more than 30 years’ experience in social work, youth work and justice roles. Keith was a member of the Welsh Government’s National Children’s Safeguarding Forum as well as a panel member of the Family Justice Review.