fˈɜːθ hɐz ɛndʒˈɔɪd ɐ kənsˈɪstənt ˈæktɪŋ kɚɹˈɪɹ ɪnðə θˈiəɾɚ ænd hɐz ɐpˈɪɹd ɪn nˈuːmɚɹəs tˈɛlᵻvˌɪʒən pɹədˈʌkʃənz, ɪŋklˈuːdɪŋ dʒˈiːvz ænd wˈuːstɚ, ðə bˈɪl, ðə jˈʌŋ ˌɪndiːˈænə dʒˈoʊnz kɹˈɑːnɪkəlz ænd mˈɑːɹɡɹət.
Firth has enjoyed a consistent acting career in the theatre and has appeared in numerous television productions, including Jeeves and Wooster, The Bill, The Young Indiana Jones Chronicles and Margaret.