A judge has labelled a man who encouraged young girls to kick him in the groin a 'bizarre predator'.

Driving instructor David Aston, 32, is facing jail after enticing the teenagers - aged 13 and 14 - into satisfying his "bizarre" sexual tastes by bribing them with alcohol and cash.

The married father-of-two met one of the girls in an Internet chatroom and told her he had starred in videos for websites catering for people who liked being kicked.

Oxford Crown Court heard Aston twice stripped naked from the waist downwards, crouched on all fours on a towel in woodland near Bicester and encouraged four girls to kick him in the groin until he could no longer handle the pain.

A jury of nine men and three women found Aston, of Bell Close, Cassington, guilty of two counts of sexual activity with a child and four of causing or enticing a child to engage in sexual activity.

They also cleared him of five counts of making indecent images of children.

Peter Coombe, prosecuting, had described Aston as a "predator" who targeted vulnerable young girls and corrupted them.

Judge Julian Hall said: "This particular fetish is not one I have come across before.

"I found this a bizarre case. The description of predator is not ill-founded and the overwhelming probability is you are going to go to prison."

During the five-day trial the court had heard evidence from the youngsters, who described their "shame and disgust" at agreeing to kick Aston.

Giving evidence earlier in the week, one of girls, who was 14 at the time of the two incidents in April 2006, admitted lying to Aston by telling him she was 16 and said he had asked her to pose for dirty pictures.

Two other girls, then aged 13 and 14, also admitted telling Aston they were each a year older than they were - but still under the age of consent.

The court heard Aston met the girls on two separate occasions with one going along twice and three others once each.

He engaged in sex acts with one of them in the front seats of his car while others looked on from the back.

Aston, who denied all the charges, had claimed he believed the girls were all aged 16 or over because they were wearing make-up, smoking and drinking.

The court heard his marriage had since broken down, but he was now in a new relationship and still had a close bond with his two sons, aged five and seven.

Judge Hall adjourned sentencing until Monday, June 16, released Aston on bail and ordered him to sign the sex offenders' register.