Another political role for Nettleton was a Conservative Party Member of Parliament in the sitcom The New Statesman. A veteran actor with a career spanning many decades, Nettleton is easily at home playing troubled or flawed aristocratic gentlemen or can be seen amongst a comic ensemble. Other television roles included a Ministry of Defence department chief in The Avengers (episode "The See-Through Manitoba", 1967), a police sergeant in Please Sir! (1969), Francis Bacon in Elizabeth R (1971), a Detective Superintendent in Doctor at Large in 1971, Upstairs, Downstairs (1972), The Country Wife (1977), Brideshead Revisited (1981), The Flame Trees of Thika (1981), The Citadel (1983), Martin Luther, Heretic (1983), Brass (1983), East of Ipswich (1987), Reverend Ernest Matthews in the Doctor Who serial Ghost Light (1989), Longitude (2000), Midsomer Murders (2005) and Kingdom (2008).
On stage, he has appeared in the Lyttelton Theatre of the National Theatre in the 2006 productions of Harley Granville Barker"s The Voysey Inheritance, directed by Peter Gill.
He also voices Grandpa in the Personal Computer Game, "The Scruffs". In the 1960s and 1970s, Nettleton was the reader of various illustrated stories on children"s television programme Blue Peter.
Often these were about historical figures, such as Florence Nightingale.