Where one co-accused contemplates murder and the other contemplates only robbery, there is no common criminal purpose capable of supporting either a murder or manslaughter conviction of the non-perpetrator on the basis of joint criminal enterprise. The acts of the principal offender in committing murder are so far outside any understanding of robbery as to constitute a separate and distinct crime. Following [name withheld] v The Queen, where manslaughter has not been left to the jury in a case where it was open on the evidence, the test for the application of the proviso is whether a jury, properly instructed, would necessarily have returned a verdict of guilty of murder in any event.
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