Richard Ayoade, Harriet Dyer, Bob Mortimer, Tom Allen, Ian Smith

Jimmy Carr hosts a combination of the comedy panel show and the long-running words and numbers quiz, with Richard Ayoade and Harriet Dyer taking on Bob Mortimer and Tom Allen. Regular Countdown mathematician Rachel Riley and lexicographer Susie Dent are on hand to adjudicate, Joe Wilkinson drops in and Ian Smith joins Susie in Dictionary Corner.