“… we should emphasise that even a cursory glance … makes it plain that the sentence is concerned with future risk and public protection. Although punitive in its effect, with far- reaching consequences for the offender on whom it is imposed, strictly speaking, it does not represent punishment for past offending. As any such assessment of future risk must be based on the information available to the court when sentence is passed, the potential for distraction from the real issue is obvious. Nevertheless, when the information before the court is evaluated, for the purposes of this sentence, the decision is directed not to the past, but to the future, and the future protection of the public.”