Oscar-winning film-maker and actor Mel Gibson makes his first appearance on the show, joined by hilarious star of Anchorman Will Ferrell, actor and producer Mark Wahlberg and award-winning stage and screen star John Lithgow. Later they are joined by the new head judge from Strictly Come Dancing, Shirley Ballas. Plus, singer-songwriter Kesha performs Learn to Let Go. Providing there's time, Graham will also subject more audience members to the dreaded red chair - so their stories had better be good.