Matthew Lewis, who plays Neville, has undergone a bigger physical transformation than any other person who works in those films to the point that, when I went to the read through of Half Blood Prince, we were all sitting in this great square and they put all the tables from the Great Hall into this big square so everyone’s facing inwards for the read through. And facing me were Dan, and Rupert, and Emma, and Evanna, and Bonnie, and the main lot. And there’s this really big cool guy sitting there, with a bit of stubble and wearing this woolen hat, and a leather jacket, and I didn’t recognize him, and my eyes pass on, and I sort of thought, ‘That will be the guy they’ve got playing McLaggen’. And then I thought, ‘Where’s Matthew?’ and I looked at him and my god, when did that happen? -JK ROWLING