Security officer Daniel Vickers, 32, of Churchill Court, Newmarket, had no licence or insurance when he drove his boss's 4x4 over a roundabout in Fordham in July last year, while going 100mph and swerving from side to side.

Vickers hit Andrew Grove, of Exning, then 15, and his friend Louis Haley, then 16, as they rested on the roundabout on their way home from a party in a nearby village. Vickers then reversed back over Andrew, before driving off, leaving both boys with grave injuries.

He later set fire to the jeep in a bid to destroy any evidence before eventually turning himself in.

Louis suffered a broken back, a fractured skull and serious brain damage – injuries that left him on a life-support machine.

Andrew suffered serious head injuries, a fractured jaw and pelvis and was left with a blood clot on the brain.

Vickers was sentenced to indefinite imprisonment for public protection at Cambridge Crown Court on April 22 after pleading guilty to dangerous driving, arson and a count of fraud.

At the time, Judge Jonathan Haworth told Vickers he was someone who had "little regard for the law" and represented a "serious risk to the public".

Almost identical to a life term, the IPP sentence meant Vickers could have no hope of release until he could convince the parole board he was safe to live in the community.

But on Thursday, Lord Justice Moore-Bick, sitting with Mr Justice Beatson and Judge Peter Jacobs at London's Appeal Court, quashed the sentence and replaced it with a conventional four-year jail term.