Best recognized for playing Nigel in the blockbuster film series Harry Potter. He also had small roles in the films An Education and Vanity Fair.
After making his television debut in Smack the Pony in 2001, he then had a brief recurring role in William and Mary in 2004.
In 2014, he joined the cast of Fried as Joe.
His father, Julian Firth, is also an actor and his mother's name is Gilliam. His sister Isabella is, like him and his father, also an actor.
In Vanity Fair, he portrayed the younger counterpart to James Purefoy's character Rawdon Crawley.