A 13 year old boy suffered a broken skull when a 15-year-old boy kicked his head at a party 2005.

In May of this year, a judge ruled that the parents holding the party had not provided enough supervision. But three Appeal Court judges have recently ruled that it was a freak accident.

Lawyers for the couple had argued they had acted no differently from "parents up and down the land". The couple were originally found liable for damages, estimated at more than £1m, for the boy, who now needs round-the-clock care.

The accident happened during the seconds that the mother had gone to help a child on bungee run inflatable, also hired for the birthday party.

The appeal judges said that the mother could not be held at fault for the "freak and tragic accident". They added "The manner in which she was supervising activities on the bouncy castle and the bungee run accorded with the demands of reasonable care for the children using them".

The injured child brought the case against the couple through his mother. He was 11 when a much taller and heavier boy, caught the left side of his head with a heel.

Lord Phillips said that children played alone or with others in a wide variety of circumstances.  "It is impossible to preclude all risk that, when playing together, children may injure themselves or each other, and minor injuries must be commonplace," he said. He went on to add, "It is quite impractical for parents to keep children under constant surveillance or even supervision and it would not be in the public interest for the law to impose a duty upon them to do so."

Lord Phillips said the child's injury was of "horrifying severity" but could not reasonably have been foreseen. The mother had acted reasonably in thinking she could supervise both inflatable's at the same time.

The judges awarded costs against the injured child and refused permission to appeal to the House of Lords. But they "stayed" costs pending any future application to appeal to the Lords.