He pleaded guilty to ABH. Looking at the sentencing guidelines, this would appear to be a Category 2 offence in that it is lower harm (the boy did not suffer serious injury) but higher culpability (targeting a vulnerable victim, possibly hostility due to the victim's age, etc.). That means the starting point for sentencing is 6 months with a range from low level community order to 51 weeks in prison. There are a number of aggravating factors (presence of others, gratuitous degradation of victim, abuse of position of trust and possibly others that are not evident in the press reports) but I can't see anything in the reports that suggests any mitigating factors, so we are going to move up from the starting point. I don't know at what point in the process the barber first pleaded guilty so I'm not sure how much discount he got for that. If he pleaded guilty at the first possible opportunity he would have got a one third reduction in the sentence, meaning that he got 51 weeks less the discount for pleading guilty. If he waited until the case got to court he would have received a smaller discount.
Overall I think the sentence is harsh but it appears to be within the guidelines. The thing I find most surprising is that the sentence was not suspended.
It was pretty much inevitable that something like this would happen since the High Court sentenced a man to 12 months for ABH in 2006 after he cut off his girlfriend's ponytail without her consent. Before that the lower courts tended to take the view that cutting someone's hair without consent was not an offence.
Is this the same judge who let a man off with 40,000 serious sexual images of children on his computer because the evidence bag tag was wrongly done so couldn't be submitted in court
I am not familiar with that case. Do you have a link? But, based on your description, the judge would not have let the man off. The prosecution would have withdrawn its case. It is not the judge's fault if the police mess up the evidence. From the description you give it sounds like the police were unable to prove that the evidence was gathered from the defendant and had not been tampered with. If you want to convict people on dodgy evidence we are all in danger. Blame the police, not the judge.