A Royal Air Force police officer's career is in ruins after a judge jailed him for a year for indecently assaulting a 13-year-old girl.

Married father-of-two Damian Marshall started a relationship with the schoolgirl after sending her a text message in which he asked if she was a virgin.

A jury found him guilty of one offence of sexually abusing the teenager but he was cleared on three further allegations of indecent assault and one of indecency with a child. Sentencing him yesterday, Judge James Stewart QC criticised the 35-year-old for not owning up to what he had done.

"You knew what you were doing was wrong. Indeed it is referred to in one of the letters, but you didn't have the courage to admit your guilt,'' he told him.

"You ran this case to the wire causing this girl to give evidence and be cross-examined.''

Bradford Crown Court heard that the girl, who cannot be identified for legal reasons, had consented to the relationship and, as well as exchanging text messages and letters, Marshall had also discussed his sexual fantasies with her.

"You befriended this girl. You allowed her to confide in you about her personal problems. You visited her at school and you took her quite inappropriately to some local woods,'' said Judge Stewart.

"The law is there to protect young women against themselves and against people like you.''

Marshall's barrister Julia Nelson said he had been in the RAF since he was 17 and had an exemplary record.

"Your Honour, the conviction is the end of his career in the RAF,'' said Miss Nelson.

She said Marshall, of Taunton Street, Shipley, also faced losing the home provided by the RAF and 18 years of pension rights.

Miss Nelson invited Judge Stewart to consider a non-custodial sentence which would involve Marshall being made the subject of sex offender programme. But Judge Stewart told Marshall: "Those in positions of trust must learn that if they act as predators on young girls they will be punished.''

In addition to jailing Marshall for 12 months he also ordered him to register as a sex offender for the next ten years and banned him from working with children for the same period.