Year Title Role Notes 2004 Hawking George Ellis Television film 2004 Agatha Christie: A Life in Pictures Max Mallowan Television film 2005 Beethoven Ferdinand Ries 2 episodes 2006 Bombshell Lieutenant Roddy Frost 7 episodes 2006 Holby City Martin Phillips Episode: "Looking After Number One" 2007 Doctor Who Mysterious Man Episode: "The Lazarus Experiment" 2008 John Adams Lord Carmarthen Episode: "Reunion" 2009 Primeval Ryan Mason Episode 3, Season 2 2009 Waking the Dead Dr Dench 2 episodes 2009 Midsomer Murders Justin Hooper Episode: "The Great and the Good" 2010 Sherlock Sebastian Wilkes Episode: "The Blind Banker" 2010 Just William Uncle Neville Episode: "Parrots for Ethel" 2011 The Crimson Petal and the White Ashwell 3 episodes 2011 Hidden Alexander Wentworth 4 episodes 2012 Restless Mason Harding Episode: "Part Two" 2014 Babylon Finn Kirkwood 7 episodes 2014 The Wrong Mans Nathan Cross Episode: "White Mans" 2015 Coalition Nick Clegg Television film 2015 Jonathan Strange & Mr Norrell Jonathan Strange 7 episodes 2015–present Doctor Foster Simon Foster Two series, lead role 2016 Revolting Rhymes Various voices 2 episodes 2017 The Crown Robin Day Episode: "Marionettes" 2018 Big Cats Narrator[18] 3 episodes 2020 The Pale Horse Zachariah Osborne 2 episodes 2020 Baghdad Central Frank Temple 6 episodes 2020 The Sister Bob 4 episodes