Holly Grogan died after plunging 30ft from a road bridge near her home on to a dual carriageway, where she was hit by passing traffic. She was found at 11pm on Wednesday under a bridge in Churchdown, Gloucestershire, two miles from her home.

Steve Grogan, 45, and his wife Anita, 44, from Longlevens, Gloucester, said they were devastated by the death of their "wonderful" daughter, which followed the posting of dozens of abusive and humiliating messages on her Facebook wall.

Her family said in a statement: "Holly struggled to cope with the huge pressures placed upon her by the modern complexities of 'friendship groups' and social networking."

It added that they were "sure every responsible parent will empathise with our constant battle to instil self-belief and confidence in our children. Holly's outwardly vivacious zest for life was apparent to all who knew her."

It emerged that Holly, who went to £11,600-a-year St Edward's school in Charlton Kings, Gloucestershire, had been subjected to months, if not years, of cyber-bullying.

A friend, Chloe Davis, 16, said Holly had moved to the fee-paying Catholic school in the past year in an attempt to escape her tormentors. She said: "Holly was nice and had the biggest smile in the world. She always did well at school but the other girls used to pick on her. She didn't have any confidence, that was the problem.

"Girls used to gang up on her and call her names and she didn't have anything to say back. She just froze up. They used to leave comments on her Facebook wall, calling her names."

The family statement said they had chosen the school "in the belief that the morals and values promoted by the school would provide Holly with a platform to the next stage of her life".

Chloe spoke of rumours that bullies at Holly's previous school had urged their friends at her new school to continue their abusive behaviour.

Dozens of tributes to Holly were posted on a local newspaper website and on an online tribute page. Her 17-year-old brother, Tom, wrote that her family "loved to her bits". Her cousin, Laura, said: "She was a beautiful girl with a beautiful family and had some wonderful times with so many people, clearly touching so many people's lives."

A Gloucestershire police spokesman said: "A formal identification and a post-mortem examination are now in the hands of the coroner. We are appealing for any witnesses to come forward." Holly's death is not being treated as suspicious.

St Edward's headteacher Andrew Nash said the school was in "shock" but refused to speculate on whether staff had been aware of the bullying.