A gunman shot at a van driver in a road rage attack after following him for seven miles.

The victim believes the motorist was angry at being blocked off at a roundabout at the M40 Oxford Services at Wheatley.

He then followed his van to Thame along the A418 before firing and shattering the rear window.

The 42-year-old van driver from Oxford said the incident was sparked when the other motorist got in the wrong lane and there was no room to let him in.

Police are appealing to witnesses for information on the gunman who was driving a black car - possibly a BMW - last seen on the A4129 driving away from Thame.

The van driver said: "There was a little altercation at the Wheatley junction when he was in the wrong lane and tried to cut in front of me. But I was in the right lane and I couldn't let him in.

"The guy was mad but there was no need for what he then did. He followed me up to the roundabout, but we weren't racing, so I didn't think I needed to get his registration. I could see him in the mirror.

"When I turned left at the roundabout, I looked and saw he was pointing out of the passenger window at the van.

"As I turned, the gun went off and the window got blown out. It was a bit scary.

"The only thing I could think of was that it was road rage after what happened earlier. He must have thought I'd cut him up."

He did not stop the van, but drove to Aylesbury before believing it was safe to pull over and alert the police.

He added: "My hope is that someone might know who it was and he gets caught.

"You wouldn't think this kind of road rage would affect you, but I'm pretty shaken."

The first altercation took place on the roundabout at the A418 junction with the M40, near the services, shortly after 7am on Wednesday. Police are trying to get CCTV footage from the junction.

The van driver was in his red Volkswagen van going towards Thame, when he noticed the black car following behind.

The shot - from an airgun - was fired about 20 minutes later and seven miles further on, as he turned on to the A418 Aylesbury Road at Thame.

The pellet has not been found.

Thames Valley Police spokesman Rebecca Webber said: "Scenes of crimes officers have been looking at the van and we have been trying to track down the car.

"But it has been difficult because we have no registration number.

"The driver of the van believes it was road rage and that's one angle we're looking at."

Anyone with information on the shooting should call police on 08458 505505 or Crimestoppers on 0800 555111.