Two youths, aged 16 and 17, were arrested and  charged with murder. But the pair admitted manslaughter on the eve of their trial.

The 16-year-old pleaded guilty to manslaughter and possession of an article with a blade or point on Monday. The 17-year-old admitted the same charges yesterday.

Old Bailey judge Ann Goddard asked for probation reports to be prepared before sending the killers to jail. She said: “It must be understood that this is not with a view to a community sentence. It seems to me custody is the appropriate sentence.”

The defendants cannot be named for legal reasons. But as she remanded them in custody, the judge said she would consider lifting the identity ban at sentencing, which she set for April 4.

Joanna Korner, QC, prosecuting, said the 17-year-old admitted punching Mr Anil during a scuffle after the wrapper was thrown.

She added: “Having done so, he was confronted by the deceased and a verbal dispute ensued.

“There was some physical contact involving the deceased grabbing the

T-shirt of the defendant. This resulted in the defendant punching the deceased.

“The defendant took out a knife to frighten the deceased but he says he did not intend to use it. He then passed it to the 16-year-old.”

The younger defendant denied threatening the victim with a knife but admitted being involved in the fight.

Miss Korner said passerby Derek Porter went to get help from nearby Gipsy Hill police station – but it was closed as it was a Sunday.

In his statement, Mr Porter also said the lout who tossed the half-eaten Lion bar had acted like a “gunfighter from a Western” when challenged by Mr Anil. 

Another witness, Susan Hunt, said the victim hit his head “heavily against the kerb” as he fell.

Mr Anil, of Upper Norwood, was only a week into a new job after graduating with a first class honours degree in computer science.

The youngest of four children, he came to the UK from Turkey at the age of three with his father, Niyazi, 52, a retired caterer, and mum Altun, 48.

Mr Anil was a talented footballer and played in a Sunday league in Croydon.

His sister described him as “an angel”. In a statement read out in court, she said: “I have contemplated suicide to ease my pain. My brother Ozgur has had to receive psychiatric treatment. I will forever have a broken heart.”