A teenager who died at a music festival suffered a cardiac arrest, an inquest opening has heard. Lucy Ellen Halpin, 18, died on 11 July after going to the Tonnau festival near Llanfaethlu on Anglesey. At the time, organisers of Tonnau festival confirmed that the festival had been cancelled to enable the authorities to carry out their inquiries. Opening and adjourning the inquest on Tuesday, the coroner said she extended her deepest sympathies to Lucy's family. "Lucy wasn't just staff, Lucy was a member of our extended family and was treasured by us, our customers and her colleagues, many of whom became her close friends.