A suspended police community support officer, accused of masturbating behind the wheel as he watched a teenage girl walking down a street, has been convicted.

Former soldier Kelvin Mackenzie, 49, of Lincolnshire, denied committing an act which outraged public decency in St Albans, claiming it simply wasn't him or his car.

But a jury of eight men and four women at Chelmsford Crown Court did not believe him and took just over an hour to reach their guilty verdict.

Judge Christopher Morgan indicated Mackenzie would not be going to prison and adjourned sentence for reports until the week of 22 February. He was released on bail.

Witness Adam Barnes, about to go out on a cycle ride at 4.50pm on 30 July 2014, said he saw the driver through an open window of a red Renault Megane, as it slowly passed him in Faircross Way, St Albans.

"When he drew level I could see that he was struggling. I assumed he was trying to put his seat belt in but as I looked in the window I could see what he was doing.

"The passenger window was open. I saw his penis in his hand. It was erect. He was going up and down with his right hand. His left hand was on the steering wheel.

"He was looking straight ahead. There was a girl walking along on my side of the pavement, about 16-17, slim, wearing a skirt," the witness told the jury.

Prosecutor Alex Rooke said the driver appeared to be "fixed" on the young girl.

Giving evidence, Mackenzie, a full-time PCSO since 2005, said his car was not in Faircross Way at any stage on that day.

He had finished his shift at St Albans police station at 4.30pm and was leaving the city for his two-hour journey home.

His route took him close to Faircross Way but he did not drive down it. He had moved to Cowfield Gould, Holbeach, in November 2012.

He suggested that the witness had made a mistake in the registration number he wrote down, that the number might be very similar to his, or cloned.

Mackenzie, who served in the Royal Anglian Regiment, including in Northern Ireland in his early 20s, is of previous good character.

He had arranged a transfer to Cambridgeshire as a PCSO to be closer to his new home when the allegation was made and he was suspended.