Eight years seems a very short amount of time, and personally, I think the 'good behaviour' clause should work the other way. If you're sentenced o 8 years, you do the full 8 years, and if you MISbehave, then extra time is taken off.
Under current legislation, you get out early for good behaviour, but that doesn't seem right to me - good behaviour is the very minimum that should be expected.
Also, whilst eight years seems like a very light sentence, we have to remember, they were not done for murder, but for manslaughter. Their ages would've also been taken into consideration.
With regards to Chris Preddie - I don't think it's his duty to put this killer back on the straight and narrow. His OBE (whether you believe it was well deserved or not) was for working with others, prevening them from going down that path, not for acting as a parole officer.
There is something quite admirable with someone who spends their spare time actually getting down and doing something about gangs and youth crime.