Vansittart has been married to Emma Kate Watson since 1987. They have two children. In 2000, young Actress Emma Watson was asked to star in the new Harry Potter film, so Emma Kate Watson changed her name to Emma Vansittart, adopting her husband's surname as her new stage name.
In 1993, he appeared in Remains of the Day as Sir Geoffrey Wren, a character based on the 1930s British fascist Sir Oswald Mosley.
In 1994, he appeared in the film Braveheart as Lord Bottoms. He worked in Four Weddings and a Funeral as George the Bore at the Boatman in 1995. In 2003, he appeared in the West End adaptation of Arsenic and Old Lace.
Vansittart is known to fans of the 1995 Pride and Prejudice serial as the actor who portrayed Mr Hurst, the brother-in-law of Charles and Caroline Bingley. He has also worked with Rowan Atkinson on a number of occasions, appearing as a guest star in two episodes of Mr. Bean and also The Thin Blue Line, as well as appearing in Johnny English Reborn, the sequel to Johnny English.
In 2005, he appeared in the "Market for Murder" episode of Midsomer Murders and, that same year, as General Asquith in the two Doctor Who episodes, "Aliens of London" and "World War Three". In 2006, Vansittart portrayed Thomas J. Dodd in the BBC three-part drama documentary Nuremberg: Nazis on Trial. He also appeared in the 2008 BBC serial Spartacus as Consul Lentulus,
2009 also saw his second appearance in "Midsomer Murders", in an episode titled "The Dogleg Murders". In 2010, he appeared in Doctors as Anthony Chippington, a friend of Charlie's. He played Harrison Ashton Lard, the "posh girl's father", in How Not to Live Your Life. He provided additional voice-over for World's Craziest Fools. He appeared in the final two seasons of Foyle's War as Sir Alec Myerson, the title character's boss at MI5. Vansittart also appeared in the BBC Three comedy Bad Education, playing Mr. Humpage. Since 2014, Vansittart started playing Lord Yohn Royce in the HBO series Game of Thrones, making recurring appearances in season 4, 5, 6, and 7.
In 2016, he appears in the BBC TV series Father Brown as Arthur Le Broc in episode 4.7 "The Missing Man". In January 2016, he played character Peter Jennings on an episode of the BBC series Casualty.
