The mother of an 11-year-old boy killed when he was crushed by a large branch in woodland in Norfolk has started a £300,000 compensation claim.
Daniel Mullinger, of West Bergholt, Essex, died while taking part in an orienteering exercise at National Trust property Felbrigg Hall in June 2007.
Daniel's mother, Wendy Mullinger, is suing the National Trust for bereavement over the loss of her son.
The National Trust has denied liability in the High Court case.
Daniel was among a group of 10 children undertaking a "Monster Trail" search for clues scattered around the grounds of Felbrigg Hall, near Cromer, when he was killed instantly by the falling 21-metre (70ft) branch.
Three of his fellow pupils from Heathlands Church of England Primary School were severely injured in the incident, the court heard, and their parents are also suing the National Trust over the accident.
Daniel's parents were too distressed to attend the hearing on Tuesday as the claimants' QC, Jonathan Watt-Pringle, outlined the case against the National Trust.
The branch fell from a mature beech tree estimated at between 150 to 180 years old, Mr Watt-Pringle told Mr Justice Mackay, as the group of children were walking through the Great Wood at Felbrigg Hall.
He acknowledged that the National Trust had in place a system of regular inspection designed to ensure that no trees were a risk to the public.
But he claimed that the tree in question should have been designated a "high risk" and urgent steps taken to prevent the branch becoming a deadly hazard.
The QC said the claimants recognised that the National Trust was a body which "provides a significant service to the public".
He added: "The case is not about whether or not they provide that function well, but whether on this particular occasion - when dealing with this particular very mature tree - they discharged the duty imposed on them by law."