By Katie Timms & Tim Hanlon Parents found out that their two-year-old girl had a serious condition when her legs turned yellow at nursery. Tom, 38, and Rachael Barker, 37, rushed Clara to the Bristol Royal Hospital for Children on the advice of their GP after the nursery called them to say her legs had changed colour. They were told that she had a liver problem and then they were transferred to Birmingham Children’s Hospital where doctors said Clara had acute liver failure and urgently needed a new liver. “It all happened incredibly quickly. Clara was at nursery and I got a call from them sayi…