Career: Armstrong made his film and TV debuts in 1994 in There's No Business and A Breed of Heroes. He was introduced to Ben Miller in 1996 and their subsequent success at the Edinburgh Festival Fringe led to their first sketch series in 1997; they've worked together a number of times since on various projects. Armstrong played the lead in short-lived sitcom Beast. He has also appeared in Birthday Girl (2001), I Saw You, TLC, Saxondale, Life Begins, The Trial of Tony Blair, Mutual Friends, Woody Allen's Match Point (2005) and Scoop (2006). Armstrong was the voice of supercomputer Mr Smith in The Sarah Jane Adventures, appeared in the 2011 Doctor Who Christmas Special and has presented the BBC game show Pointless since 2009. In recent years, he has also voiced Danger Mouse in the revival of the animated series and presented Rome's Invisible City, Land of the Midnight Sun and Don't Ask Me Ask Britain.

Career: In 1999, O'Brien made his film debut in Virtual Sexuality. His other film credits include 24 Hour Party People (2002), 9 Songs (2004), Goal! The Dream Begins (2005) and Goal II: Living the Dream (2007). More recently, he has starred on the small screen in Bluestone 42, Silk, Grantchester, The Syndicate and Prey.