Of course, public understanding is not helped when the prosection lawyer makes such misleading comments as the one quoted by the BBC:

"The judge has to determine first of all the notional sentence, which in this case was 18 years. Then that is cut by half to reach the actual sentence. Then the judge is obliged to cut a third off in view of the guilty plea."

By "notional sentence" he means "maximum term spent in prison". By "actual sentence" he means "tariff, i.e. minimum term spent in prison before he becomes eligible for parole". In fact, this quote is so misleading that if it was reported accurately I can't believe it wasn't intended as deliberate misinformation.