A man has told a court he saw a pensioner's car reverse over and kill a teenager as she was filling her car up with petrol.

Alexander Caldwell said he tried to find and rescue Eilish Herron after she was swept away by Alexander Wotherspoon's "screaming" silver Ford Focus.

He said he eventually found her trapped under Wotherspoon's vehicle after it came to a rest in some bushes at the edge of the garage forecourt in Linwood, Renfrewshire.

Wotherspoon, 83, is on trial at Paisley Sheriff Court where he denies causing 17-year-old Ms Herron's death by driving without due care and attention at the Asda petrol station in on September 10, 2014.

He denies breaking Section 2B of the Road Traffic Act 1988 by starting the engine of his car and reversing while the driver's door was still open.

The charge against Wotherspoon states his actions knocked Ms Herron to the ground, moved her car out of the way and caused his car to reverse over her, dragging her underneath the car, "causing her to be so severely injured that she died."

On Tuesday, Alexander Caldwell said he witnessed the moment Ms Herron was struck by Wotherspoon's car as she filled up her blue Renault Clio.

The unemployed 39-year-old explained: "I saw the wheels spinning backwards, I heard the screaming of the tyres. The lady was standing at the pump putting in petrol.

"The back of the car went up and went up on to her car's bonnet and started to turn on its side.

"It came down full force on top of Eilish. It all went so fast - it was like I did see it but I didn't see it.

"The silver car went straight back and slightly to the left. It ended up about 20ft away from the pump."

He added: "I ran straight over to Eilish's car to try and find her. I went behind the car, I thought maybe she'd been hit backwards but she wasn't there.

"I looked underneath the car but she wasn't there. I looked back at the pump and saw the pump handle had broken off. I couldn't find her anywhere, I was perplexed by that."

Mr Caldwell said it was only after failing to find Eilish that his fiancee, Rachel Cleary, told him what had happened to her.

He explained: "She had seen it dragging her round to where it ended up in the bushes. I wasn't aware of that straight away.

"I ran over to the car and dove underneath it and tried to assist the patient - as I did a bit of first aid when I was younger.

"I looked at Alexander [Wotherspoon] and he stared straight ahead - he was totally unresponsive to me.

"His wife seemed to be giving him instructions - quite clearly, if I may say so.

"The paramedics didn't have a jack when I got there so I got one from my own car.

"And there was one from one of the other first responders in a Land Rover - they slowly lifted the car and removed Eilish."

A joint minute of agreement was read to the five male and ten female jurors in Wotherspoon's case, setting out the events which led to her death.

The joint minute stated that Wotherspoon's Ford Focus struck Herron's blue Renault Clio, pushing it backwards, and that the Focus then hit Ms Herron before coming to a halt.

The document added: "The accused, Alexander Wotherspoon, was driving a silver Ford Focus.

"The Ford Focus struck Eilish Herron and said Ford Focus then came to a halt. Paramedics actioned to attend at the Asda filling station had to remove Eilish Herron from underneath the Ford Focus and in to an ambulance where she was treated.

"She was pronounced dead at 2.56pm. The cause of death was a head injury due to a road traffic injury."

The document, which was read to the jury by the clerk of court, also stated that Wotherspoon, of Houston, Renfrewshire, has had two hip operations and a knee replacement, uses two sticks to help him walk and has been left with a shorter right leg because of the procedures.

The trial, before Sheriff Seith Ireland, continues.