"He was standing with another man, Martin Byrne, discussing the weather. Mr Byrne saw the blue Vauxhall Corsa car come round the corner from the direction of Kilclief," he said.
"Mr Byrne said the car lost control and started to spin around and rotate in an anti-clockwise direction and ended up facing the wrong way.
"The car had struck the Land Rover Discovery and also Mr Wilkinson, trapping him underneath the vehicle."
The court heard that the Corsa had been following a black Seat Cupra and earlier that day the cars were spotted on CCTV driving through Ballyhornan at speeds of 30mph and 20 metres apart.
Mr McDowell said: "Mr Wilkinson died at the scene from his injuries. He was 72."
He added: "The deceased's daughter, Pauline Magee, saw her father underneath the car. She was screaming 'call 999, call 999'.
"She shouted at McManus, 'Look what you have done you b******. You have killed my father.'
"McManus gesticulated to her and gave her the middle finger.
She replied to McManus: "Some day you will know what it is like to have this pain."
The expert witness said in a report that he was unable to calculate what speed the Corsa was travelling at before the collision, but he estimated that as the car "spun around and rotated it was travelling at a speed of between 40-51mph".
Judge Grant heard the victim impact statements on the deceased's family described as "heart wrenching in nature".
"This family have faced this case with dignity and compassion," said Mr McDowell, who added: "They accept that these defendants did not go out that day to kill anyone."
During sentencing, Judge Grant condemned McManus for gesticulating at Mrs Magee at the crash scene, stating it showed "little remorse" for his actions.
"I take the view that anyone who behaves the way that you did by gesturing obscenely shows little remorse whatsoever and shows a high culpability," he said.
"You do not behave in that way even if you are involved in a minor collision.
"This was highly reprehensible and disgusting behaviour on your part," he added.
Passing sentence last week at Downpatrick Crown Court, Judge Piers Grant told the defendants that photographs of the accident on the Killard Road in Ballyhornan, Co Down showed a "scene of devastation".
He added: "You two alone, by your driving on that day, caused the death of Mr Wilkinson.
"It is only right that I acknowledge the great loss suffered by the Wilkinson family. He was clearly a good man, a much loved and respected individual and he has now been taken away by your irresponsible behaviour. You will have to carry that burden for the rest of your lives.
"You will appreciate that your actions have resulted in the death of an entirely decent man who moved with his wife to be with his daughter and son-in-law during a difficult time in their lives and you will carry that for a considerable period of time.
"His family will have to live with the dreadful circumstances for a long time. I commend the Wilkinson family for the Christian charity they have expressed," he said.
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