If an adult using an imitation firearm had robbed the same small store twice in 31 days, he would have received a sentence of 16 years’ imprisonment after being found guilty by a jury.

Last year, a young man, who committed those same offenses at the age of 15, received a sentence of eight years. This week, the Court of Appeal upheld the sentence.

The defendant, referred to as D, robbed a West Bay mini-mart in March and April 2016. He turned 16 a few months later and pleaded not guilty. After trial, the jury’s guilty verdicts were unanimous and Justice Charles Quin passed sentence after receiving social inquiry and medical reports.

The appeal court said Justice Quin was clearly right to regard 16 years as the appropriate sentence for an adult. The U.K. Sentencing Guidelines for Children and Young Persons set an adjustment of one-half to two-thirds for a young person.

Crown counsel Greg Walcolm, who prosecuted D, brought evidence to show that the teenager had worn a mask and that both robberies had occurred at night. On the first occasion, D had what appeared to be a firearm in his pants waist; on the second occasion, he pointed the weapon directly at the shop clerk.

Attorney Keva Reid argued on appeal that the value of the goods stolen was fairly low: cash and cellphones valued at $1,805 the first time, $450 and cigarette papers the second time.

The same clerk had been on duty during both robberies and had then quit after continuing to have nightmares, the court heard. The owner subsequently shut down the store. The appeal judges said the robberies had lasted a short time but were clearly terrifying.

Referring to submissions concerning D, the judges commented, “He has really a wretched background.” Professional evaluations referred to attention deficit, mood and learning disorders, and difficulty with self-control due to personality disorder.

The judges said D had been in trouble with police from an early age. At the time of the robberies, D was wearing an electronic monitor in relation to other charges. “No one reading this background can fail to sympathize with the difficulties he has faced,” the judges said in their decision.

At the Grand Court sentencing hearing, Ms. Reid had told Justice Quin about at least three efforts before the robberies to get D into a treatment center abroad.

The U.K. sentencing guidelines set out overarching principles to be considered for young people, noting they are likely to benefit from opportunities to address their behavior, may far more rapidly change and benefit from treatment, and for whom heavy punishments are likely to have far greater impact.

“All of that is particularly relevant to this young man,” the appeal court said.

The appeal was heard by Sir John Goldring, president; Justice John Martin and Justice Sir Alan Moses.