Britain’s Got Talent was off to a dramatic start on Wednesday's live semi-final after Simon Cowell disagreed with co-judge David Walliams over Les Sancho's performance. During the opening of the show, Les Sancho put on an energetic performance to which Simon, 62, buzzed the act off by pressing the dreaded red button.The judge, who was called "Mr Grumpy" by hosts Ant and Dec, then told the booing audience: "Shut up!" Delivering his feedback, Simon told Les Sancho that their first audition was full of "fun" and "personality" whereas their performance on Wednesday's semi-final was "everything he has seen before with a dance group".