Gary Dobson and David Norris were 17 and 16 respectively at the time of the racist murder of Stephen at a bus stop in London in 1993.

Mr Justice Treacy had indicated that the convicted killers – found guilty this week – would face a minimum stretch of 12 years rather than the 25 an adult would face for knife murder.

However, according to The Telegraph newspaper, the judge will take into account that the murder was racist and that the pair knew that one of their gang might use a knife when deciding on sentencing.

The judge told the court: “We have seen and heard material about the attitude of Mr Norris and Mr Dobson which suggests to me a mind set prepared to contemplate violence against black people if they were members of a group they happened to come across.

“So whilst this may not have been a premeditated attack on Stephen Lawrence it seems to me premeditation is nonetheless a factor.”

It has taken 18 years for anyone to be convicted of the black teenager’s murder, after the initial investigation of the crime was famously mishandled and led to an inquiry into institutional racism in the Metropolitan Police.

Stephen’s mother, Doreen, said after the trial: “How can I celebrate when my son lies buried, when I cannot see him or speak to him? When I will not see him grow up or go to university, or get married or have children. These verdicts will not bring my son back.”

She added that the verdict could have come 18 years earlier if the police “who were meant to find my son’s killers” had not “failed so miserably”.