Christopher Omoregie, now 28, was one of three teenagers found guilty of murdering 15-year-old Sofyen Belamouadden at a busy London tube station in 2010.
He was handed a life sentence with a minimum term of 18 years at the Old Bailey in April 2012.
Following his rehabilitation while in prison, a High Court judge recommended on Thursday that Omoregie’s minimum term should be reduced by one year, giving him a chance of an earlier release on parole.
Sofyen was chased into the ticket hall at Victoria underground after a clash between two rival school groups, and stabbed to death in a “sustained and vicious attack” in front of horrified commuters in March 2010.
Police stopped the attackers, who had fled on a bus, and found one of the knives used to stab the teenager in Omoregie’s bag.
In his, ruling Mr Justice Dove said: “It is clear that the murder of the deceased has had a devastating effect upon his immediate family, who continue to mourn his loss and have difficulty in coming to terms with the events of that day.
“The deceased was unarmed and the manner of his death, being hunted down and killed by (Omoregie) and others in the college group, continues to cast a very long shadow over the lives of those who were close to the deceased.”
One of the features of Omoregie’s time behind bars, reviewed as part of the judge’s decision, was the therapy programme named Psychodrama which went on to inspire his brother’s album.
Accepting the £25,000 Mercury Prize at a ceremony in 2019, Dave explained the album was inspired by his brother’s therapy and added: “I want to thank my brother Christopher. Even though you can’t be here with us today, I know you are watching this bro.”
On his album, Dave describes Christopher as “the only person I ever idolised” and reveals how appalled and let down he felt by his incarceration, rapping: “Never had a father and I needed you to be a figure.”
“This is all his story. His Psychodrama inspired this,” he told the BBC. “This album’s always been dedicated to him, so to see it translate is something I can’t put into words.”
The judge’s ruling included a report from the therapist who conducted the course, who said Christopher Omoregie had brought “much warmth, enthusiasm and humour” and was good at “communication, tolerance, warmth and generosity”.
Early in his sentence, Omoregie had described his mother and brothers as “protective factors”, who had stood by him, and said it was important for him not to “let them down” again in future.
He also prepared a letter for Sofyen’s family as part of a restorative justice programme, and had invited the judge who tried his case to an event in prison – during which they discussed the case, which Omoregie found “cathartic”.
A 2020 report highlighted by Mr Justice Dove described Omoregie as a “bright man, with a very positive record of behaviour in prison”.
The report said he has studied for a degree in philosophy and psychology with the Open University, and hopes to do a master’s degree on completion of that course.
It also concluded he “shows a very high level of remorse towards the victim and the victim’s family” and had “taken responsibility for his offending”.
Omoregie will be able to apply to the Parole Board one year sooner as a result of the judge’s decision, but will only be released when the board is satisfied he does not pose a danger to the public.