A police officer has kept his job after a four-letter road rage row at a motorway toll booth where he fumed at a Mercedes driver.

PC Dean Harris, 47, was driving on the M4 when he allegedly grabbed the wing mirror of the passing Merc.

The Mercedes driver – named only as Mr W – heard a “bang” before he saw PC Harris pull alongside him saying: “You smashed my f***ing mirror.”

A misconduct hearing was told PC Harris had been hanging out of his car window shouting – and later started to flash his lights.

PC Harris escaped losing his job at Gwent Police and was instead handed a final written warning for gross misconduct.

Panel chair Susan Davies was told the road rage row took place as PC Harris drove through tolls on the Severn Bridge from England into Wales.

Jonathan Waters, representing the force, said PC Harris was “incensed” by the alleged collision and leaned out of his window to grab the driver’s mirror.

Mr Waters said: “PC Harris attempted to damage the mirror by hitting it with his open hand and pushing it as far as it could go.”

The Merecedes driver also claimed he felt PC Harris “shunting” the back of his vehicle.

The driver then called police on his way home to report the incident – not realising PC Harris was an off-duty officer.

Giving evidence, the driver said there were “three or four distinct lanes” of traffic as he drove through the tolls into Wales on the M4.

He had let one driver into his lane but saw a red Vauxhall, driven by PC Harris, on his passenger side.

He said: “He kept shouting “You smashed my f***ing mirror.

“He was grabbing my mirror and he was rocking it back and fore and he was swearing.

“He was hitting it with the butt of his hand and then it turned the wrong way.

“The man was so angry he was trying to damage my car and I moved forward so he couldn’t do any more damage.”

He added: “It was going through my mind that he was doing his best to inflict damage to my car.

“When somebody cuts into a lane of traffic you are in, I don’t think you are at fault.”

The hearing was told PC Harris then got out of his car to confront the driver on November 9, 2018.

But the driver left the scene as he was “quite fearful.”

PC Harris, based in Blackwood, denied five allegations of breaching Standards of Professional Behaviour.

He has now been handed the final written warning following the hearing in Cwmbran, South Wales.

A Gwent Police spokesperson said: “PC Harris has received a final written warning, following the outcome of the hearing.”