A MARRIED driving instructor who asked schoolgirls to kick him in the groin today denied having an "unhealthy interest" in children.

Father-of-two David Aston, 32, took the stand at Oxford Crown Court and said he was told by one of the four girls they were all over 16.

The jury was told the girls were all underage when he asked them to kick him as he knelt on his hands and knees with no underwear on.

Aston told the court he met one of the girls through an Internet chatroom and arranged to pick her and her friends up in his red Honda Civic.

Aston, from Bell Close, Cassington, denies sexual activity with a child, causing or enticing a child to engage in sexual activity and making indecent photographs of children.

He said he started chatting to the girl on MSN Messenger and told her he had posed as a model in a video for a website catering for people who liked being kicked in the groin.

He said: "She was very keen to meet up. She was keen to do the kicking. I believed that she was 16 because she told me online."

The court heard Aston met the girl on two occasions in April 2006, and three of her friends, who came along once each, and drove them to secluded woodland near Bicester before asking them to kick him.

He said: "(One of the girls) said they were 16 in their presence and neither said anything."

He told the court on the first occasion the two girls performed a sex act on him in his car before agreeing to kick him, but he denied the girls' claims that further sex acts took place in the car on the second occasion.

Aston said: "They all had make-up on and were dressed up and all looked 16. They were all smoking."

He told the jury he had never seen the indecent images of children police said they found on his computer and suggested his friends could have downloaded them.

Peter Coombe, prosecuting, said Aston's ten-year career as a driving instructor put him in a position of trust. Referring to one of the girls, who was 14 at the time, he said: "I am going to suggest it is perfectly obvious, looking at her, she is nowhere near the age of 16.

"If that girl had applied to you for driving lessons there is no way you would have let her in your car, would you?"

Aston denied the girl looked under 16, but said he would have checked her driving licence before giving her lessons.

Mr Coombe added: "You made an arrangement with a girl to satisfy a sexual lust that you had and you were not going to let anything stand in the way of that.

"You had an unhealthy sexual interest in young girls. You liked to sexually abuse girls yourself that were underage and you knew perfectly well were underage."

Aston denied all Mr Coombe's claims. The trial continues.