STORMBREAKER author ANTHONY HOROWITZ has dropped star ALEX PETTYFER from the next movie installment - because he is too old. Horowitz insists the 17-year-old actor won't be reprising his role as Alex Rider in the film series, as he is now too grown up to play the child sleuth. Stormbreaker hit cinemas in 2006 and the popularity of the book series - which includes seven novels so far - could see the film expand into a major franchise. But Horowitz wants a new, younger actor to take over the role of the hero - who stays 14 years old throughout the books. He says, "It was a conscious decision to keep him (Rider, the main character) at that age. Alex Pettyfer is a strapping young man so even if we were to go ahead and make the sequel, Point Blank, I don't think he would have been up for it, even if the character had got a bit older." The novelist is also critical of the decision to keep Daniel Radcliffe on in the title role of the Harry Potter movies. He adds, "Daniel was beginning to look a bit adult in the films."