Shirley Tinch was created by writer and penciler Peter Gross in The Books of Magic number 57, in 1999.
Major Story Arcs
Shirley Tinch was best friends with Holly Ransome, who had a history of bad relationships with men, who were always using and lying to her. Shirley once drunkenly told Holly she should try being with someone she's not attracted to, and Holly decides to take her up on it. She starts seeing Bill Hunter, father of Tim Hunter.
However, Shirley thinks that it is a terrible idea for her to actually do this. She tells Holly that if she continues seeing Bill, then she is essentially betting their friendship on the relationship, because Shirley can't watch Holly self-destruct. She has had her own string of bad relationships, and knows how bad it is.
Holly's relationship with Bill starts off well, but ends up going horribly due to her son Cyril and events related to Tim's involvement in the world of magic, and Holly is eventually killed. Her dying words are that she lost her bet.
Shirley shows up at the funeral and sadly meets Bill and Tim.