Donald Bennett, from Pudsey, Leeds, died from chest injuries after he was hit by the van as it rolled down a slope in a park in June 2013, Wakefield Coroner’s Court heard.
The inquest heard that a female police officer was speaking to a group of youths about an incident in Pudsey Park when the unmanned vehicle began moving.
Lawyers told the inquest there were a number of explanations for the van to move, including the handbrake not being applied, or not being applied sufficiently, a mechanical failure or the handbrake being released as a “terrible joke” or “accident”.
The inquest heard that Mr Bennett, who walked with two sticks following a hip replacement and was on medication for a heart condition, had gone to the park on June 1 2013, to watch the bowls. His wife, Margery Bennett, had given him money for an ice cream.
Jessica Smith, from London, told the jury she was in the park with her father when she saw Mr Bennett walking slowly down the slope,with a walking stick in one hand and an ice cream in the other.
Miss Smith said she immediately noticed the police van rolling down the slope directly behind Mr Bennett.
“He wasn’t able to get out of the way in time,” she said. “The van made impact with Mr Bennett, knocked him off his feet. It continued to roll forwards until he was no longer visible, he was trapped underneath.”
Miss Smith said people tried to lift the van from Mr Bennett using a car jack but were unsuccessful. She said another man lay on the floor holding Mr Bennett’s hand and comforting him.
Craig Smith, from Leeds, was at the park with members of his family and said Mr Bennett was sitting on a wall immediately prior to the collision.
He said he noticed the van moving around 90 seconds after the police officer arrived and entered a nearby building.
Mr Smith told the inquest the van clipped Mr Bennett’s shoulder as he stood up, causing him to fall to the ground and become trapped underneath the vehicle, which came to a stop when it collided with an ice cream van.
He said: “It struck him on his right shoulder. He got up but he had two sticks, he fell into the path of the van, he fell at an angle because of the steepness of the hill. Then after that it was the left hand side of the van that actually took him to the floor, first his legs disappeared, then he came flush with the van and the rest of the van took him under.”
He added: “It was just so unreal what had happened.”
Both witnesses told the court they saw the police officer after the collision.
Mr Smith said she appeared to be “in shock” and did not know what to do.