'Where the charge is murder and in the rare cases where the simple direction is not enough, the jury should be directed that they are not entitled to find the necessary intention unless they feel sure that the death or serious bodily harm was a virtual certainty (barring some unforeseen event) as a result of the defendant's action and that the defendant appreciated that such was the case. The decision is one for the jury to be reached upon consideration of all the evidence.' (Per Lord Steyn.)