A mother accused of negligence after a boy suffered a catastrophic accident on a bouncy castle during her triplets’ birthday party was acting no differently than thousands of other parents, a court heard.

So argued top QC, Graham Eklund, who is representing Catherine Perry of Jersey Road, Strood, in her Appeal Court fight to prove she was not to blame for the accident which wrecked an 11-year-old boy’s life.

Sam Harris, now 13, suffered a fractured skull after being struck in the head by a somersaulting older boy whilst jumping on the inflatable at a September 2005 party in Rochester, Kent, organised by Mrs Perry and her husband, Timothy, for the tenth birthday of their triplets.

High Court judge, Mr Justice David Steel, in May this year ruled there had been a “shortfall in supervision” by Mrs Perry and that had caused Sam’s devastasting accident.

The ruling opened the way for Sam, who lives with his mother, Janet Harris, of Greenways, Long Lane, Gedney Hill, Spalding, Lincs, to claim up to a million pounds compensation for his injuries.

However, Mr and Mrs Perry are now challenging the judge’s decision at London’s Appeal Court, where their case is being heard by the nation’s top judge, the Lord Chief Justice, Lord Phillips, along with Lord Justice May and Lord Justice Wilson.

Mr Eklund, said: “There was no obligation on Mr and Mrs Perry to provide sufficient supervisors to watch all parts of the ground all the time. Mrs Perry’s conduct was within an appropriate and acceptable range.”

But Susan Rodway QC, for Sam, said there should have been “uninterrupted supervision” of the bouncy castle by the Perrys during their triplets’ birthday party and Sam should never have been allowed to play on it with a much larger, taller and heavier 15-year-old.

The bouncy castle on which 11-year-old Sam Harris came to grief was “inherently dangerous” and Catherine and Timothy Perry’s appeal is an exercise in “plain disgruntlement”, the court was told.

After half a day of legal argument, the Appeal Court judges reserved their decision on Mr and Mrs Perry’s appeal in the bouncy castle case.

The court is expected to give its ruling before the end of the current legal term on July 31.