By Kieren Williams Here are nine missed chances that authorities may have had to stop the Nottingham knife attacker. Valdo Calocane attacked and killed two university students as they walked home after a night out. He then tried to break into a homeless hostel, before stabbing school caretaker Ian Coates 15 times, and stealing his van, using it to ram into three others. Barnaby Webber, Grace O’Malley-Kumar, both 19, and Ian Coates, 65, were the three victims of the attack that took place on June 13 last year. The court heard that Wayne Birkett, Sharon Miller and Marcin Gawronski were all said …