Richard Mason, 40, who had already served a four-month prison sentence for a similar offence, was told by judge Michael Mettyear that he was as an opportunist, rather than someone who prowled the streets in search of his prey.

Mason, of Furlong Avenue, Norton, pleaded guilty in 1995 to an indecent assault on a teenager while working as a security officer at Flamingo Land.

Sarah Mallett, prosecuting, told York Crown Court how Mason had approached one of the girls when he was naked.

The girl had refused his advances and, after threatening to tell, was grabbed by the neck and thrown on to a sofa.

The youngster told the court that, although she reported the physical attack, she was too frightened to tell anyone of the indecent assault until she heard that Mason had sexually assaulted another girl.

No action was taken against Mason at the time but, following the complaint from the second girl, he was charged with all the offences.

Mason told the jury that he could not understand why any of the girls had made the allegations.

His barrister Ruth Cranige suggested that the girls had either been making the stories up or seeking attention. Both denied the claim.

Miss Cranige told the court that the inevitable prison sentence would have adverse affects on Mason's current partner, her children and his 61-year-old mother.

Mason was also placed under a 10-year Sexual Offence Prevention Order which bars him from having unsupervised contact with any female under the age of 16.

He was also placed on the Sex Offenders' Register and barred from working with children for life.