This has turned into quite an interesting topic with a real mixed bag of views coming out - thanks for your contributions.
At present, there does not appear to be any evidence to link youths to this crime. This sort of behaviour, no matter who is behind it is totally unacceptable and many of the arguments above can be applied no matter who is responsible.
If I were in charge of the youth justice scheme I would be much tougher from the start, and would make sure that repeat time offenders were given much harsher sentences. I believe that everyone should be able to make one mistake - after all we learn from our mistakes, so I would still keep the existing reprimand for minor youth offences and make it clear that further offences will have much higher consequences.
On a second offence, I would then make the following offer:
If found guilty, a person under 16 must either participate in a relevant community project for a prescribed period of time (at least one year in lenght around school hours) to teach dicipline, team work, hard work, but on a successful completion, the criminal record is non-disclosable to employees so as maximising chances of getting into gainful employement and less likely to end up on benifit etc. Regular school attendance would be essential, as work progression to best of ability within school. Failure to complete will result in custodial sentence at YOI
If found guilty, a person over 16 must either enter the military service for a mimimum period of 2 years, or go directly to jail. Military service will have all the ususal benifits including pay, commaradery, prospects etc. Failure to complete 2 years will result in jail term being completed.
This is not national service as it is a voluntary decision by each participant. It also does not punish the well behaved either.