Wearing hoodies and scarves over their faces, he and two accomplices assaulted the cashier of the BP garage in Mill Lane, Kingsthorpe, before making off with £268 takings from the till.

At Northampton Crown Court yesterday, the 19-year-old was sentenced to 21 months' detention for the robbery, with 18 months consecutive for a house break-in and 34 other similar offences.

At one stage during the hearing, the judge, Recorder Sam Mainds, told him: "Stop laughing. This is a serious matter."

Passing sentence, he added: "You have an appalling record for a young man and have been very busy for the past 15 months committing serious offences."

Michael Waterfield, prosecuting, said Ali, Luke Clarke, 18, and another youth who has not been traced, covered up their faces before entering the petrol station at about 9.30pm on November 10.

When asked to remove their masks, the cashier was punched in the face before his mobile phone was taken, along with cash from the tills.

The court heard Clarke, formerly of Woodside Way, Kings Heath, had only agreed to join in the robbery at the last minute, kept lookout and opened the doors to the garage shop while the two others stole money.

However, he ran off when the violence escalated and received none of the stolen money. Having pleaded guilty to robbery, he was given nine months' youth custody.

The judge said: "Your situation is more different. You are of the same age and fell in with thieves, serious thieves and there is nothing particularly innocent about you.

"This kind of offence has got to be dealt with by a custodial sentence for the protection of those who run these sorts of premises at night, for other shopkeepers and as an example to the young."

Ali, formerly of Hester Street, Semilong, was one of the ringleaders of the 'Aldi Crew' known to terrorise St James' shoppers and residents.

Sentenced to 21 months' detention at a young offenders' institution for the attempted robbery of a pizza delivery driver in December last year, he was also given a three-year anti-social behaviour order banning him from Victoria Park, the car park of Aldi supermarket in St James and from drinking or being drunk in public.

Stephen Crouch, for Ali, said: "His family have now disowned him for obvious reasons."