21 The direction under s 24 was, as I have said, more favourable to the appellant than any which might have been given under the second limb of s 248. In either case the jury had to find that the appellant had been assaulted by Mr McCallum. However the second limb of s 248 was only applicable if, as I have said, the jury found that the assault on the appellant was such as to cause a reasonable apprehension of death or grievous bodily harm. No such requirement pre-conditioned the operation of s 24 as outlined by the learned trial Judge. In the case of the second limb of s 248 the jury had to find, if the defence there provided for was to be available to the appellant, that the appellant believed, on reasonable grounds, that he could not, otherwise than by using the degree of force used by him, defend himself or his friend from death or grievous bodily harm. If a defence under s 24 was to be available the jury had, on the direction given by the learned trial Judge, to find that the appellant mistakenly but honestly and reasonably believed (and there is, I think, no sensible distinction between a belief on reasonable grounds and an honest and reasonable belief) that the degree of force used by him was necessary to make effectual defence. The learned trial Judge told the jury that the relevant mistake, in this context, would be one which related to the appellant's belief that, unless he used the degree of force in fact used, he could not make an "effectual" defence. It is difficult to imagine that the jury could conceivably have thought, in the light of a direction of this kind, that if the appellant was not mistaken in his belief (that is to say, if he did in fact need to use the degree of force used by him to make effectual defence) then he should be convicted. It would be quite absurd for the members of the jury to have thought that they should acquit him if he was mistaken in that belief but that they should convict him if he was not. They would, no doubt, have thought that they should acquit him in either case.