Born in Ashington, Northumberland, Oliver was introduced refereeing by his father, Clive, at the age of 14. He quickly progressed through the ranks and was promoted to the National List of Referees in 2007; he refereed the 2007 Conference National play-off Final, becoming the youngest football referee to officiate at Wembley Stadium. In addition he had already become the youngest Football League assistant referee, and would also become the youngest fourth official in the Premier League.