He appeared in Remains of the Day (1993) as Sir Geoffrey Wren, a character based on the 1930s British fascist Oswald Mosley.

In 2006, Vansittart portrayed Thomas J. Dodd in the BBC three-part drama documentary Nuremberg: Nazis on Trial.

[4] He has also played political characters on stage: in 2014 he was one of the main actors in the cast of Great Britain at the Royal National Theatre.

He appeared in the final two seasons of Foyle's War as Sir Alec Myerson, the title character's boss at MI5.

[2] In 2014, Vansittart started playing Lord Yohn Royce in the HBO series Game of Thrones,[1] making recurring appearances in season 4, 5, 6, 7 and 8.

[1] In 2016, he appears in the BBC TV series Father Brown as Arthur Le Broc in episode 4.7 "The Missing Man".

[2] Vansittart has been married to Emma Kate, daughter of the actors Moray Watson and Pamela Marmont, since 1987.