Pertwee trained at Bristol Old Vic Theatre School, after graduating in 1986 he toured with the Royal Shakespeare Company for three years. He appeared in Agatha Christie's "Hercule Poirot – The King of Clubs" alongside David Suchet (12 March 1989). He later appeared as Hugh Beringar alongside Derek Jacobi in the first series of the television series "Cadfael" in 1994. In 1999 he portrayed Brutus in the Hallmark Channel film "Cleopatra". He co-owned the Natural Nylon film production company along with Sadie Frost, Jude Law, Jonny Lee Miller, and Ewan McGregor. The company folded in 2003. Pertwee is perhaps best known for his portrayal of grimacing death, particularly in the film "Dog Soldiers", a skill which led to him being given an award for 'Best Death Face' at Bristol Old Vic.