R v McInnes [1971] Edmund Davies LJ : "but where self defence fails on the ground that force used went clearly beyond that which was reasonable in the light of the circumstances as they reasonably appeared to the accused, is it the law that the inevitable result must be that he can be convicted of manslaughter only, and not of murder? it seems that in Australia that question is answered in the affirmative ... but not, we think, in this country. On the contrary, if a plea of self defence fails for the reason stated, it afford the accused no protection at all"