There was nothing in the background of Yussuf Mustapha to suggest he would become Britain’s youngest gun killer.

The immigrant son of devoutly religious parents, whose older sister is an accountant in Birmingham and brother a sound engineer, the 14-year-old was regarded by his teachers as a keen student and an avid sportsman.

He had no known connection to gang activity, or indeed any other blemish on his record.

However, on Monday, he sat in the dock at Birmingham Crown Court with his head in his hands, jailed for life for a murder of the most extreme savagery.

In January, Yussuf Mustapha was one of a gang of five boys, aged between 14 and 17, who launched a frenzied attack on Keon Lincoln, 15, outside his home on a tree-lined street in Handsworth, north of Birmingham.

The gang chased down Keon then hacked at him with hunting knives and machetes, stabbing him eight times in 30 seconds. While he was lying on the ground, Mustapha – who had already fired once at his victim and missed – delivered the fatal wound by shooting him in the stomach with a revolver, which has never been recovered.

As the gang fled in a stolen Ford S-Max car, Sharmaine Lincoln, Keon’s mother, rushed outside to find her son dying on the pavement.

In court on Monday, she described the killers as “heartless, evil monsters”, adding: “The gun shots will forever ring in my ears, knowing that one of them ended my son’s life.”