Exactly a week later, his abductor, Howard Small, 30, was arrested 300 miles from the scene of the crime in Guildford, Surrey, as he tried to lure newspaper boys into his car.
Small was in Darlington, Co Durham, to take up a job with the Forestry Commission as a countryside ranger which involved showing children around forests, the court was told.
Sentence on Small, of Worthing, West Sussex, who admitted abducting the boy and buggering him, was adjourned for reports.
Anthony Leonard, for the prosecution, said the attack happened in March this year. The boy was helping his parents and others decorate a school hall for a barn dance when he asked to go to a jumble sale in another school building, 200 yards away.
As he made his way there, he passed Small who followed him and took him to his car. Small then drove to a park two miles away and sexually assaulted the boy in a public lavatory.
The boy gave police a description of his attacker and an impression was drawn by the BBC artist Julia Quenzler. A copy of the drawing was sent to Darlington after Small's arrest, and he was immediately recognised as the Guildford attacker.
Ms Quenzler said the boy was one of the best witnesses she had ever worked with. 'He was remarkable. His recall for detail was exceptional. I can't praise him enough.'
Detective Sergeant Michael Bobryzk, of Guildford police, said the boy was still receiving counselling.