(Michael Crabtree/The Times) Lydia Playfoot, who says her school is discriminating against her for banning her from wearing a purity ring (Michael Crabtree/The Times) The ring that Millais School banned Lydia Playfoot from wearing A teenage girl who was banned by her school from wearing a "purity ring" is taking her case to the High Court today. Lydia Playfoot, 16, is a member of a Christian group called the Silver Ring Thing and one of a number of students at the Millais School in Horsham, West Sussex, who wears a silver ring engraved with a Biblical reference — "1...