Sandman, you are incorrect. GTO is right- There has to be a REAL threat to your well being and safety to you and/your family to use deadly force. If an intruder is running for the front door and you shoot him in the back in your living room that's manslaughter. Likewise if an intruder is a 3 foot tall 12 year old armed with a wooden spoon and he advances on you and you shoot him 9 times in the chest that also is manslaughter due to the lack of legitimacy of a 12 year old's threat.
Basically the Courts have to decide when that self defense turns into aggression, and in this case they decided it was somewhere between the third and fourth thrust in the perp's back with a butcher knife on the front lawn.
I'm amazed none of you have stated the obvious here- Britian needs to ban knives and crowbars and this violence will stop. After all, Britain has no need for knives cause they don't eat beef anymore due to Mad Cow disease.