Marcia Grant, who was also a grandmother, was fatally injured in Greenhill, Sheffield, on 5 April.

The offender - who was 12 at the time and cannot be named for legal reasons because of his age - was sentenced at Sheffield Crown Court on Wednesday.

He struck Mrs Grant outside her home despite the frantic attempts of her husband, Delroy, to stop him, the court heard.

The judge, Mrs Justice May, described the 60-year-old victim as the "shining lodestar" of her family.

"You made a bad choice," the judge told the boy as she passed sentence. "You knew that taking her car was wrong."

She said the offence "was serious but it was not murder", and the prosecution had accepted the boy did not mean to harm Mrs Grant.

"It was a very bad accident," the judge added.

The court heard the boy had never driven before and struggled to control the Honda Civic when he reversed into Mrs Grant, knocking her over and driving over her.

He fled the scene saying "sorry, sorry". When he was arrested after trying to run away from police, he told a policewoman: "I'm going to f****** kill your family you b**** and I don't give a f***."

The boy asked officers: "Is she dead?" before saying: "It was an accident, I swear," five minutes later.

The victim's daughter, Gemma Grant, said her mother "wanted to pull the world into a hug, lend a hand and raise the spirits of anyone facing adversity".

"We will never forgive him and will carry this trauma with us always," she said in a statement to the court.

'Looks like I got my first kill'

The child pleaded guilty to causing Mrs Grant's death at a hearing at the city's youth court last month.

A charge of murder was dropped by prosecutors when they accepted the plea.

Describing the incident, prosecutor Gary Crothers told that hearing the boy said "looks like I got my first kill" to police afterwards.

"At around 7pm on the evening in question this defendant is seen on CCTV attempting to take Mrs Grant's car. Mrs Grant tries to stop him by going behind the car," he said.

"On CCTV, the vehicle is driven slightly erratically at this time and it does come to a stop.

"Mrs Grant positions herself behind the vehicle. The vehicle reverses, causing her to fall on her back and her head impacts with the ground.

"She was trapped under the vehicle, her husband tried to break the window of the car to get the defendant out of the car."

The prosecutor said the vehicle then reversed "at some speed causing the catastrophic injuries to Mrs Grant".

The youth claimed to have been a gangster since aged nine.

Richard Wright KC, mitigating, said the boy had had "an extremely challenging childhood".

In a prepared statement to police, the defendant said he was taking the car so he could drive to see his mother.

'No closure' for victim's family

Mrs Grant's family released a statement after her death, describing her as a "warm, loving and dedicated wife, mother, grandmother, sister and friend and a pillar of her community".

In a statement, released through the police, on Wednesday, they were critical of the CPS and said the "torture" of the last eight months had been compounded by the reduction in criminal charges.

"We strongly believe that the evidence on hand shows a complete disregard for human life and clear premeditation to do serious harm," they said.

"Our mother was killed on her own driveway by a young person wearing a balaclava, carrying a stolen knife, and in the act of stealing her car when he ran her over not once, but twice."

They added: "We are completely heartbroken that our mother will not get the justice she deserves."

They also criticised Rotherham Council, saying it "played a critical role in the circumstances which led to our mum's death".

Nicola Curley, Strategic Director of Children's Services at Rotherham Council, said the authority had launched an independent partnership review into the circumstances surrounding the case "to ensure that any potential processes and practices are considered".

"As one of our foster carers, Marcia was well known, much-loved and highly respected in our fostering community," the council said in a statement.

"She selflessly provided generous love and care to vulnerable children who needed it the most and she is sadly missed by all those who knew her well. Our thoughts continue to be with her family."

Detective chief inspector Andrea Bowell said: "Since Marcia's death our thoughts have been with her family and friends after she was taken from them in the most difficult of circumstances."

She added: "Her death has had a profound effect on everybody who loved her. Although the criminal justice process has concluded today, I'm aware this brings no resolution or closure for Marcia's friends and family.

"They will continue to grieve their tremendous loss and will do so for the rest of their lives."