Ritson is best known in recent years for playing King Edward III in the TV miniseries World Without End (2012), the Duke of Kent in Upstairs Downstairs (2010-2012), Mr Elton in the 2009 BBC adaptation of Emma, Edmund Bertram in the 2007 ITV adaptation of Mansfield Park, Giles Vicary in the BBC series Red Cap and for portraying sidekick Robert Presley in A Touch of Frost. He also played the part of Justin in The League of Gentlemen, Idek in God on Trial, and the comic lead in For Elsie, an Oscar-winning short film, which he also co-produced. He also portrayed the main antagonist in David Goyer’s Da Vinci’s Demons (2013).