He made his first class debut in 2007, at the age of 17. Against Gloucestershire, he finished with figures of 12-118, meaning he became the youngest player ever to take 10 or more wickets in a County Championship match, taking 5-52 in the second innings to follow up his first-innings 7-66.
Amazingly Harris rapidly followed this up by becoming the youngest Glamorgan player to score a half century with the bat as he posted an impressive 87 not out in a record 9th wicket partnership of 185 with Robert Croft against Nottinghamshire at Swansea, in only his fourth first class match.