A 65-year-old pervert was caught thanks to children hiding in a park to listen as he chatted up their 12-year-old friend, a court has heard.

The youngsters hatched a 'sting' operation to trap Richard Johnson after he had molested the 12-year-old girl the previous day at a ballooning event in Berkeley where he was a steward.

When the hidden children heard Johnson asking the girl to return to the park to see him that night they emerged from their hiding place and confronted him, Gloucester crown court was told.

Police went to the park that night to find Johnson waiting in his car for the girl – just as the children had said he would be.

Johnson, of The Croft, Cam, Dursley, pleaded guilty at Gloucester crown court to sexually assaulting the girl on August 5 this year and to possessing an indecent image of bestiality at his home.

He was jailed for eight months, placed on the sex offender register for ten years and banned from working with children. A 15-year sexual offences prevention order was also imposed.

Judge Susan Evans told him the offences were so horrible that he had to go to prison despite his previous good character. He had breached his position of trust as a steward at the event, she said.

Prosecutor Lisa Hennessy said the girl and a ten-year-old friend went to the balloon event at Berkeley Football Club on August 10.

The girl needed the toilet during the afternoon and approached Johnson to ask where it was.

"He took her to the pavilion and unlocked it," said Mrs Hennessy. "They both went inside and Johnson locked the door."

Johnson proceded to touch the girl in inappropriate places before unlocking the door, Mrs Hennessy told the court.

The next morning the victim, with her friends hidden close by, saw Johnson in the park and agreed to meet him later that evening.

Johnson made sexual references during the conversation and the other children emerged from hiding and told him they had heard every word.

The police were informed and when Johnson returned to the park in the evening he was arrested.

His home was later searched and a VHS video showing an act of bestiality was found.

Chris Coleman, for Johnson, said he wished to apologise for his actions, which had been totally out of character.