CHRISTOPHER STEVENS: This ought to be called The Garyoke Challenge, but Cowell has opted instead to borrow the title of a Johnny Cash song, Walk The Line (ITV).
What s on TV Tuesday June 15: Superman And Lois navigate big twist avclub.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from avclub.com Daily Mail and Mail on Sunday newspapers.