Anna Winterbourne was a student at Sharadine School during the 1990s, beginning her education there in 1991. Anna was half-blood, coming from a family with a number of brothers and sisters who also went to Sharadine, including one named James.

At the end of her first year in 1992, she timidly asked Thomas Erwin, her embittered Transfiguration professor, why he seemed to hate Harry Potter. He refused to answer, but was clearly perturbed by the question. Anna refused to tell even her parents what she had said to Erwin that had upset him so. Even two years later, some of the other students still tormented her to try and find out what she had said to him. After returning from his 1994 Hogwarts visit, Erwin chose to confide in Anna. Anna was sympathetic and he told her that she was the only one who understood his pain a little.

In 2005, Anna delivered Harry Potter a letter which told him about Erwin and walked away.