A man who performed a sex act in front of a schoolgirl on a bus, was arrested by the victim’s father – a policeman waiting for her at the next stop.

Hugh White, 48, and his victim were travelling on the U1 from Oxford city centre to Wheatley when the incident occurred.

Having alerted the driver and got off the double-decker, the victim fled in tears to her father’s nearby car. He boarded the bus and arrested the man.

White, of Littleworth Park, Littleworth, near Wheatley, denied a charge of indecent exposure, claiming his trousers came open because of a violent emergency stop.

But a jury at Oxford Crown Court took less than 90 minutes to convict him yesterday, and he was told he was probably going to jail.

The girl, who cannot be named, told the jury she was sitting opposite White at the back of the bus at about 9.20pm on July 17 last year when, shortly before reaching her stop, she noticed his flies and top button were undone.

She said she stood up to get off the bus – metres from where her off-duty policeman father was waiting to collect her – when she saw White performing a sex act.

She told the jury: “I got in my dad’s car and started to cry and told him what had happened.

“My dad drove and parked in front of the bus, which was still parked in the layby.”

As the girl stayed in the car her father spoke to the driver, who had shut the bus’s doors to investigate, before White tried to leave.

She said: “At that point my dad held him there and sat him down on the grass by the kerb.

“He pointed to him and said, ‘Are you sure this is the man?’ and I said, ‘Yes’.”

The policeman called 999 and phoned his wife to bring his warrant card before arresting White.

In a statement, the girl’s father said: “When she got in the passenger seat she was so upset she could not tell me what had happened for several seconds.”

The bus driver’s statement said the victim looked “shocked and pale” and said of White: “His flies were undone and the male looked sheepish.”

The jury heard White was convicted in 2002 of indecent assault after fondling a woman’s bottom and left breast in Wheatley High Street, and admitted sexual assault in 2006 after grabbing a woman’s bottom in the village’s Asda car park.

During the two-day trial, White said his flies had come undone when the bus braked sharply, throwing him off his seat, and claimed the victim “misinterpreted” his nervous hand-wringing for what she said she saw.

In a transcript of White’s police interview read to the jury, an officer said the victim claimed he was performing a sex act. White replied: “In her dreams.”

Judge Bruce McIntyre told White to expect a prison sentence, adding: “Behaving in the way the jury found you did on the bus on that night, towards a teenage girl on her own, indicates to me that you have a problem.”

White was released on conditional bail to be sentenced at Reading Crown Court on December 4.