Famous for his childhood roles on the British television shows Don't Blame Me and Casualty, Hess won AFI and ACEA Awards for his portrayal of Greg King on the former series.
Early in his career, he acted in episodes of Doctors and Black Books and played the child of Naomi Watts' character in the television movie The Wyvern Mystery.
He was a series regular on the short-lived BBC sitcom Grass.
He was born and raised in Cheltenham, Gloucestershire, England.
He appeared with Haley Joel Osment and Willem Dafoe in the 2001 World War II film Edges of the Lord.