The family of an 11-year-old boy who was crushed by a large branch in woodland in Norfolk is taking legal action against the National Trust.
Daniel Mullinger, from Stanway, Essex, died while taking part in an orienteering exercise at National Trust property Felbrigg Hall in June 2007.
A coroner recorded a verdict of accidental death.
The National Trust confirmed that a civil action had been started in connection with the death.
Daniel was among 60 pupils from Heathlands Primary School, West Bergholt, taking part in the trip.
Three other children were also injured in the incident when a branch gave way.
The inquest heard from Daniel's teacher, Christine Clarke, who said the children had been sheltering from the rain under a large beech tree.
She heard a loud creak and saw the children trapped under a large branch.
Peter Griffiths, regional director for the Trust in the East of England, said in a statement: "None of us in the National Trust can imagine what a challenge the last three years have been for Daniel Mullinger's family, and the families of the other children injured in this tragic accident in 2007.
"After what the coroner described as a comprehensive investigation, North Norfolk District Council stated that, in their view, Daniel's death was an accident that was not foreseeable.
"The Coroner recorded a verdict of accidental death."
"It would be inappropriate to comment further on this civil case at such a preliminary stage."